Microfibrous cellulose aggregate, method for manufacturing microfibrous cellulose aggregate, and method for remanufacturing microfibrous cellulose dispersion liquid

ABSTRACT

A microfibrous cellulose aggregate including microfibrous cellulose having an average fiber width of 2 nm to 50 nm and a liquid compound including at least one of water or an organic solvent. The content of the microfibrous cellulose is from 6 mass % to 80 mass % per the mass of the entire microfibrous cellulose aggregate, and the content of the liquid compound is at least 15 mass % per the mass of the entire microfibrous cellulose aggregate.

TECHNICAL FIELD

The present invention relates to a microfibrous cellulose aggregate, amethod for manufacturing a microfibrous cellulose aggregate, and amethod for remanufacturing a microfibrous cellulose dispersion liquid.

The present application claims priority rights based on Japanese PatentApplication No. 2012-178345 filed on Aug. 10, 2012 in Japan and JapanesePatent Application No. 2012-178347 filed on Aug. 10, 2012 in Japan, theentire contents of which are hereby incorporated by reference.

BACKGROUND ART

In recent years, materials that use recyclable natural fibers havereceived attention due to increasing environmental awareness and for thepurpose of substituting petroleum resources. Among natural fibers, acellulose fiber having a fiber diameter of 10 to 50 μm, particularly, awood-derived cellulose fiber (pulp), has been widely used mainly as apaper product.

In addition, microfibrous cellulose having a nanometer-scale fiberdiameter is also known as a type of cellulose fibers, and the usethereof has been investigated in recent years for various applications.

Microfibrous cellulose is manufactured, for example, by a method offibrillating a beaten pulp (Patent Document 1) or a method offibrillating a cellulose raw material after treating the material withco-oxidizers such as N-oxyl and sodium hypochlorite (Patent Document 2).

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Unexamined Patent Application PublicationNo. 2012-036529A

Patent Document 2: Japanese Unexamined Patent Application PublicationNo. 2011-184825A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

With the manufacturing methods described in Patent Documents 1 and 2,microfibrous cellulose is obtained in the state of a dispersion liquid(slurry). Therefore, when the plant where the microfibrous cellulosedispersion liquid is manufactured and the plant where a product usingmicrofibrous cellulose is manufactured are separated from one another, aslurry of microfibrous cellulose is filled in a container and shipped.

However, a microfibrous cellulose dispersion liquid is prepared with alow concentration in order to secure dispersion stability, so most ofthe product that is shipped is a liquid such as water. Therefore, theshipping cost and storage costs per unit microfibrous cellulose havetended to increase.

An object of one aspect of the present invention is to provide amicrofibrous cellulose aggregate capable of reducing the shipping costand storage cost per unit microfibrous cellulose.

An object of another aspect of the present invention is to provide amethod for manufacturing a microfibrous cellulose aggregate capable ofreducing the shipping cost and storage cost per unit microfibrouscellulose. An object of yet another aspect of the present invention isto provide a method for remanufacturing a microfibrous cellulosedispersion liquid in which a microfibrous cellulose dispersion liquidwith a reduced shipping cost and storage cost per unit microfibrouscellulose can be obtained.

Means To Resolve the Problems

Several aspects of the present invention are described below.

[1] A microfibrous cellulose-containing substance comprising:microfibrous cellulose having an average fiber width of 2 nm to 50 nm;and a liquid compound composed of at least one of water or an organicsolvent; a content of the microfibrous cellulose being from 6 mass % to80 mass %; and a content of the liquid compound being at least 15 mass%.

[2] The microfibrous cellulose-containing substance according to [1],further comprising a flocculant containing a salt of a polyvalent metal.

[3] The microfibrous cellulose-containing substance according to [1] or[2], further comprising an acid.

[4] The microfibrous cellulose-containing substance according to [1] or[2], further comprising an alkali.

[5] The microfibrous cellulose-containing substance according to any oneof [1] to [4], wherein at least 40 mass % of the solid content ismicrofibrous cellulose.

[6] The microfibrous cellulose-containing substance according to any oneof [1] to [5], wherein a maximum fiber width of the microfibrouscellulose is at most 50 nm.

[7] A method for manufacturing a microfibrous cellulose-containingsubstance comprising a concentration step of concentrating amicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and adispersion medium.

[8] The method for manufacturing a microfibrous cellulose-containingsubstance according to [7], wherein the concentration step comprises aflocculation step of flocculating the microfibrous cellulose containedin the microfibrous cellulose dispersion liquid, and a filtration stepof removing the dispersion medium by filtering the microfibrouscellulose dispersion liquid after the flocculation step.

[9] The method for manufacturing a microfibrous cellulose-containingsubstance according to [8], wherein in the flocculation step, themicrofibrous cellulose is flocculated by adding a flocculant containinga salt of a polyvalent metal to the microfibrous cellulose dispersionliquid.

[10] The method for manufacturing a microfibrous cellulose-containingsubstance according to [8] or [9], wherein if a surface charge of themicrofibrous cellulose is negative, the microfibrous cellulose isflocculated by adding an acid to the microfibrous cellulose dispersionliquid in the flocculation step.

[11] The method for manufacturing a microfibrous cellulose-containingsubstance according to [8] or [9], wherein if a surface charge of themicrofibrous cellulose is positive, the microfibrous cellulose isflocculated by adding an alkali to the microfibrous cellulose dispersionliquid in the flocculation step.

[12] The method for manufacturing a microfibrous cellulose-containingsubstance according to any one of [7] to [11], the microfibrouscellulose content of the microfibrous cellulose dispersion liquid beingless than 6 mass %.

[13] The method for manufacturing a microfibrous cellulose-containingsubstance according to [12], wherein in the concentration step, themicrofibrous cellulose dispersion liquid is concentrated so that acontent of the microfibrous cellulose is from 6 mass % to 80 mass %.

[14] A method for remanufacturing a microfibrous cellulose dispersionliquid comprising a redispersion step of preparing a microfibrouscellulose-containing solution by adding a dispersion medium to themicrofibrous cellulose-containing substance obtained by the method formanufacturing a microfibrous cellulose-containing substance according toany one of [7] to [13], and performing dispersion treatment on themicrofibrous cellulose-containing solution.

[15] The method for remanufacturing a microfibrous cellulose dispersionliquid according to [14], wherein in the redispersion step, if a surfacecharge of the microfibrous cellulose is negative, the microfibrouscellulose-containing solution is adjusted to above pH 7 and below pH 12,and if the surface charge of the microfibrous cellulose is positive, themicrofibrous cellulose-containing solution is adjusted to within a rangeof pH 4 to 7.

[16] One aspect of the present invention is a microfibrous celluloseaggregate comprising: microfibrous cellulose having an average fiberwidth of 2 nm to 50 nm; and a liquid compound composed of at least oneof water or an organic solvent; a content of the microfibrous cellulosebeing from 6 mass % to 80 mass % per a mass of an entire microfibrouscellulose aggregate; and a content of the liquid compound being at least15 mass % per the mass of the entire microfibrous cellulose aggregate.

[17] One aspect of the present invention may be the microfibrouscellulose aggregate according to [16], further comprising a flocculantcontaining a salt of a polyvalent metal.

[18] One aspect of the present invention may be the microfibrouscellulose aggregate according to [16] or [17], further comprising atleast one type selected from the group consisting of acids, cationicsurfactants, and cationic polymer flocculants.

[19] One aspect of the present invention may be the microfibrouscellulose aggregate according to [16] or [17], further comprising atleast one type selected from the group consisting of alkalis, anionicsurfactants, and anionic polymer flocculants.

[20] One aspect of the present invention may be the microfibrouscellulose aggregate according to any one of [17] to [19], furthercomprising a cellulose plasticizer.

[21] One aspect of the present invention may be the microfibrouscellulose aggregate according to any one of [17] to [20], wherein atleast 40 mass % of a solid content contained in the microfibrouscellulose aggregate is the microfibrous cellulose.

[22] One aspect of the present invention may be the microfibrouscellulose aggregate according to any one of [16] to [21], wherein amaximum fiber width of the microfibrous cellulose is at most 50 nm.

[23] Another aspect of the present invention is a method formanufacturing a microfibrous cellulose aggregate comprising aconcentration step of concentrating a first microfibrous cellulosedispersion liquid containing microfibrous cellulose having an averagefiber width of 2 nm to 200 nm and a first dispersion medium.

[24] Another aspect of the present invention may be the method formanufacturing a microfibrous cellulose aggregate according to [23],wherein the concentration step comprises a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid, and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step.

[25] Another aspect of the present invention may be the method formanufacturing a microfibrous cellulose aggregate according to [24],wherein in the flocculation step, the microfibrous cellulose isflocculated by adding a flocculant containing a salt of a polyvalentmetal to the first microfibrous cellulose dispersion liquid.

[26] Another aspect of the present invention may be the method formanufacturing a microfibrous cellulose aggregate according to [24] or[25], wherein if a surface charge of the microfibrous cellulose isnegative, the microfibrous cellulose is flocculated in the flocculationstep by adding at least one type selected from the group consisting ofacids, cationic surfactants, and cationic polymer flocculants to thefirst microfibrous cellulose dispersion liquid.

[27] Another aspect of the present invention may be the method formanufacturing a microfibrous cellulose aggregate according to [24] or[25], wherein if a surface charge of the microfibrous cellulose ispositive, the microfibrous cellulose is flocculated in the flocculationstep by adding at least one type selected from the group consisting ofalkalis, anionic surfactants, and anionic polymer flocculants to thefirst microfibrous cellulose dispersion liquid.

[28] Another aspect of the present invention may be the method formanufacturing a microfibrous cellulose aggregate according to any one of[24] to [27], the flocculation step including adding a celluloseplasticizer to the microfibrous cellulose aggregate.

[29] Another aspect of the present invention may be the method formanufacturing a microfibrous cellulose aggregate according to any one of[23] to [28], wherein the microfibrous cellulose content of the firstmicrofibrous cellulose dispersion liquid is less than 6 mass % per themass of the entire microfibrous cellulose aggregate.

[30] Another aspect of the present invention may be the method formanufacturing a microfibrous cellulose aggregate according to [29],wherein in the concentration step, the microfibrous cellulose dispersionliquid is concentrated so that the content of the microfibrous celluloseis from 6 mass % to 80 mass % per the mass of the entire microfibrouscellulose aggregate.

[31] A method for remanufacturing a microfibrous cellulose dispersionliquid comprising a redispersion step of preparing a second microfibrouscellulose-containing solution by adding a second dispersion medium tothe microfibrous cellulose aggregate obtained by the method formanufacturing a microfibrous cellulose aggregate according to any one of[23] to [30], and performing dispersion treatment on the secondmicrofibrous cellulose-containing solution.

[32] The method for remanufacturing a microfibrous cellulose dispersionliquid according to [31], wherein in the redispersion step, if a surfacecharge of the microfibrous cellulose is negative, the secondmicrofibrous cellulose-containing solution is adjusted to above pH 7 andbelow pH 12, and if the surface charge of the microfibrous cellulose ispositive, the second microfibrous cellulose-containing solution isadjusted to within a range of pH 4 to pH 7.

Effects of the Invention

With the microfibrous cellulose aggregate of one aspect of the presentinvention, the shipping cost and storage cost per unit microfibrouscellulose can be reduced.

If the microfibrous cellulose aggregate of one aspect of the presentinvention contains a flocculant or an acid, the redispersibility of themicrofibrous cellulose increases when redispersed in a dispersionmedium.

With the method for manufacturing a microfibrous cellulose aggregate ofanother aspect of the present invention, it is possible to manufacture amicrofibrous cellulose aggregate capable of reducing the shipping costand storage cost per unit microfibrous cellulose.

With the method for remanufacturing a microfibrous cellulose dispersionliquid of yet another aspect of the present invention, it is possible toobtain a microfibrous cellulose dispersion liquid capable of reducingthe shipping cost and storage cost per unit microfibrous cellulose.

BEST MODE FOR CARRYING OUT THE INVENTION “Microfibrous CelluloseAggregate”

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose and a liquid compound. The microfibrous celluloseaggregate of this embodiment has a high concentration of microfibrouscellulose.

A microfibrous cellulose aggregate obtained by the manufacturing methodof this embodiment contains microfibrous cellulose and a liquid compoundand has a high concentration of microfibrous cellulose.

The content of microfibrous cellulose in the microfibrous celluloseaggregate is preferably from 6 mass % to 80 mass %, more preferably from10 mass % to 50 mass %, and even more preferably from 12 mass % to 30mass % per the mass of the entire microfibrous cellulose aggregate. Whenthe content of microfibrous cellulose is less than the lower limitdescribed above, it is not possible to reduce the shipping cost andstorage cost per unit microfibrous cellulose. On the other hand, whenthe content of microfibrous cellulose exceeds the upper limit describedabove, the redispersibility of microfibrous cellulose may decreases.

It is preferable for at least 40% of the solid content contained in themicrofibrous cellulose aggregate to be microfibrous cellulose. Here,“solid components contained in the microfibrous cellulose aggregate” arecellulose and a flocculant (at least one flocculant selected from acids,alkalis, cationic surfactants, anionic surfactants, cationic polymerflocculants, and anionic polymer flocculants). The solid componentscontained in the microfibrous cellulose aggregate may also include aplasticizer and an emulsion resin in addition to the microfibrouscellulose and the flocculant.

Furthermore, the microfibrous cellulose aggregate may containmicrofibrous cellulose, a liquid compound, and a flocculant and may alsocontain a plasticizer and an emulsion resin in addition to themicrofibrous cellulose, the liquid compound, and the flocculant.

<Microfibrous Cellulose>

Microfibrous cellulose is a cellulose fiber or rod-like particle with atype 1 crystalline structure much narrower and shorter than a pulp fiberordinarily used in papermaking applications.

In a diffraction profile obtained by wide angle x-ray diffraction imageusing CuKα(λ=1.5418 Å) monochromatized by graphite, it can be identifiedthat the microfibrous cellulose has type I crystalline structure basedon the presence of characteristic peaks at two positions around 2θ=14°to 17° and around 2θ=22° to 23°.

The crystallinity of the microfibrous cellulose determined by X-raydiffraction is preferably at least 60%, more preferably at least 65%,and even more preferably at least 70%. When the crystallinity is greaterthan or equal to the lower limit described above, even betterperformance can be expected in terms of heat resistance and a lowcoefficient of linear thermal expansion. The crystallinity can bedetermined by a conventional method using a pattern of X-ray diffractionprofile measurements (Segal et al., Textile Research Journal, vol. 29,p. 786, 1959).

(Fiber Width)

Microfibrous cellulose is cellulose having an average fiber width of 2nm to 200 nm determined by observation using an electron microscope. Theaverage fiber width of the microfibrous cellulose may be from 2 nm to150 nm. The average fiber width of the microfibrous cellulose ispreferably from 2 nm to 50 nm, more preferably from 2 nm to 30 nm,particularly preferably from 2 nm to 15 nm, and most preferably from 2nm to 10 nm. When the average fiber width of the microfibrous celluloseexceeds the upper limit described above, it becomes difficult to obtainthe properties of the microfibrous cellulose (high strength, highrigidity, high dimensional stability, high dispersibility whenconjugated with a resin, and transparency). When the average fiber widthof the microfibrous cellulose is less than the lower limit describedabove, it becomes difficult to obtain the properties of the microfibrouscellulose (high strength, high rigidity, and high dimensional stability)due to the fibers being dissolved in water as cellulose molecules.

The measurement of the average fiber width by observation ofmicrofibrous cellulose using an electron microscope is performed asdescribed below. A sample for observation via transmission electronmicroscope (TEM) is obtained by preparing a slurry containingmicrofibrous cellulose, and casting the slurry over ahydrophilization-treated carbon film-covered grid. In the case wherewide fibers are contained, an image obtained by a scanning electronmicroscope (SEM) of the surface of the slurry casted over glass may beobserved. Depending on the width of the constituting fibers, theobservation is performed with an image obtained by an electronmicroscope at any of magnifications of 1000×, 5000×, 10000×, 20000×,50000×, and 100000×. However, samples, observation conditions, andmagnification are adjusted to satisfy the following conditions.

(1) When a straight line X is drawn at an arbitrary position on theimage for observation, 20 or more fibers cross the straight line X.

(2) When a straight line Y that intersects the straight line Xperpendicularly is drawn on the same image, 20 or more fibers cross thestraight line Y

From the above described electron microscope images for observation,widths (minor axis of a fiber) of at least 20 fibers crossing thestraight line X and at least 20 fibers crossing the straight line Y(that is, a total of at least 40 fibers) are read. In this manner, atleast three sets of the above described electron microscope images areobserved, and fiber widths of at least 3 sets of 40 fibers (that is, atleast 120 fibers) are read. The average fiber width is determined byaveraging the fiber widths read in this way.

The maximum fiber width of the microfibrous cellulose is preferably atmost 1000 nm, more preferably at most 250 nm, even more preferably atmost 50 nm, and most preferably at most 30 nm. As long as the maximumfiber width of the microfibrous cellulose is less than or equal to theupper limit described above, the strength of a composite materialobtained by mixing the microfibrous cellulose and an emulsion resin willbe high, and the transparency of the composite material will be easilyensured, so the microfibrous cellulose is preferable for applicationsrequiring transparency.

(Degree of Polymerization)

The degree of polymerization of the microfibrous cellulose is preferablyfrom 50 to 1500, more preferably from 100 to 1000, and even morepreferably from 150 to 500. When the degree of polymerization of themicrofibrous cellulose is greater than or equal to the lower limitdescribed above, the microfibrous cellulose is more useful, and when thedegree of polymerization is less than or equal to the upper limitdescribed above, the redispersibility increases when the microfibrouscellulose aggregate is redispersed in a dispersion medium.

The degree of polymerization of microfibrous cellulose is measured bythe method described below.

A microfibrous cellulose (supernatant liquid obtained aftercentrifugation; concentration: about 0.5 mass %) is spread out in apetri dish formed from polytetrafluoroethylene, and dried at 60° C. toobtain a dried sheet. The obtained dried sheet is dispersed in adispersion medium, and the pulp viscosity is measured in accordance withTappi T230. The blank viscosity is also measured by performing a blanktest in which the viscosity is measured using the dispersion mediumalone. Specific viscosity (ηsp) is determined by subtracting 1 from avalue obtained by dividing the pulp viscosity by the blank viscosity.Intrinsic viscosity ([η]) is calculated using the equation below.

[η]=ηsp/(c(1+0.28×ηsp))

In the equation, c represents the cellulose content at the time of theviscosity measurement.

The degree of polymerization (DP) of this embodiment is then calculatedfrom the following equation.

DP=1.75×[η]

Since this degree of polymerization is also the average degree ofpolymerization measured according to viscometry, this degree ofpolymerization is also called “viscosity average degree ofpolymerization.”

(Fiber Length)

In this embodiment, the major axis of the microfibrous cellulose isdefined as the length. The average fiber length of the microfibrouscellulose is preferably from 0.1 μm to 5 μm. As long as the averagefiber length is greater than or equal to the lower limit describedabove, a strength-enhancing effect can be sufficiently achieved when themicrofibrous cellulose is compounded with a resin. As long as theaverage fiber length is less than or equal to the upper limit describedabove, the mixability will be better when the microfibrous cellulose iscompounded with a resin. The fiber length can be determined by analyzingan electron microscope image for observation used during the averagefiber width measurement described above. That is, from the abovedescribed electron microscope images for observation, fiber lengths ofat least 20 fibers crossing the straight line X and at least 20 fiberscrossing the straight line Y (that is, a total of at least 40 fibers)are read. In this manner, at least three sets of the above describedelectron microscope images are observed, and fiber lengths of at least 3sets of 40 fibers (that is, at least 120 fibers) are read. The averagefiber length is determined by averaging the fiber lengths read in thisway.

When the microfibrous cellulose is applied to applications requiringstrength such as a transparent substrate, the fiber length is preferablysomewhat long (specifically, from 500 nm to 4 μm), and when compoundedwith an emulsion resin, the fiber length is preferably somewhat short(specifically, from 200 nm to 2 μm).

(Anionic Groups, Cationic Groups)

The microfibrous cellulose may have anionic groups so that the surfacecharge is negative. The microfibrous cellulose may also have cationicgroups so that the surface charge is positive. In addition, themicrofibrous cellulose may have both anionic groups and cationic groups,and in this case, the surface charge of the microfibrous cellulose maybe either positive or negative. When the microfibrous cellulose has bothanionic groups and cationic groups, the matter of whether the surfacecharge of the microfibrous cellulose is positive or negative can beassessed based on the respective contents of the anionic groups andcationic groups or the valence of the anionic and cationic groups. Evenwhen the microfibrous cellulose has both anionic groups and cationicgroups, the respective contents can be measured with a method ofmeasuring the anionic group or cationic group content as describedbelow.

When the microfibrous cellulose has anionic groups or cationic groups,the content thereof is preferably from 0.06 mmol/g to 2.0 mmol/g, morepreferably from 0.1 mmol/g to 1.0 mmol/g, and even more preferably from0.2 mmol/g to 0.6 mmol/g. When the content of cationic groups or anionicgroups is within the range described above, the wettability of themicrofibrous cellulose does not become too high, and the viscosity whenformed into a slurry becomes low. When the content of anionic groups orcationic groups exceeds the upper limit described above, there is a riskthat the wettability may become too high and that the microfibrouscellulose will dissolve.

Examples of anionic groups include carboxylic acid groups, phosphoricacid groups, sulfonic acid groups, and the like. Cellulose contains alittle amount of (specifically, 0.1 mmol/g or less) carboxy groupwithout applying a carboxy group introduction treatment.

The content of anionic groups is determined using the method describedin “Test Method T237 cm-08 (2008): Carboxyl Content of pulp” of theUnited States TAPPI. The method is in accordance with TAPPI T237 cm-08(2008) with the exception that, among the test solutions used in theabove test method, the test solution containing 0.84 g/5.85 g of sodiumbicarbonate (NaHCO3)/sodium chloride (NaCl) dissolved and diluted with1000 mL of distilled water was changed to 1.60 g of sodium hydroxide sothat the concentration of the test solution substantially increasesfour-fold in order to be able to measure the content of anionic groupsover a wider range. In addition, when anionic groups are introduced, thedifference between the measured values of the cellulose fibers beforeand after the introduction of anionic groups is used as the essentialanionic group content. An absolute dry cellulose fiber of themeasurement sample is an absolute dry cellulose fiber obtained byfreeze-drying to avoid deterioration in cellulose which may occur due toheat during heat-drying.

Since the measurement method for anionic group content is a measurementmethod for monovalent anionic groups (carboxy groups), when the anionicgroups to be quantified are polyvalent, a value determined by dividingthe value obtained as the monovalent anionic group content by the acidvalue is used as the anionic group content.

A cationic group is a group having an onium such as ammonium,phosphonium, or sulfonium in the group, and the group typically has amolecular weight of at most approximately 1000. Specific examplesinclude ammoniums such as primary ammonium, secondary ammonium, tertiaryammonium, or quaternary ammonium, phosphonium, sulfonium, and groupshaving these ammoniums, phosphonium, or sulfonium.

Groups having these ammonium, phosphonium, or sulfonium preferably havegroups that react with the hydroxyl groups of cellulose in portionsother than the ammonium, phosphonium, or sulfonium. The groups thatreact with the hydroxyl groups of cellulose are not particularly limitedas long as they are reactive groups which react with the hydroxyl groupsto form covalent bonds, and examples include epoxy groups or halohydringroups capable of forming epoxy groups, active halogen groups, activevinyl groups, methylol groups, and the like. Of these, epoxy groups orhalohydrin groups capable of forming epoxy groups are preferable fromthe perspective of reactivity.

Groups having ammonium, phosphonium, or sulfonium can be introduced intocellulose by reacting a compound having these oniums with cellulose.Examples of compounds having oniums include glycidyl trialkyl ammoniumhalides such as glycidyl trimethyl ammonium chloride and3-chloro-2-hydroxypropyl trimethyl ammonium chloride, or halohydrinforms thereof.

The content of cationic groups is measured with the following method.

First, 0.5 g, in terms of absolute dry mass, of a pulp slurry that hasbeen subjected to cationization agent treatment is taken and diluted toa concentration of 1 mass % (wet weight: 50 g) with ion-exchanged water.Next, 0.67 g of a 30 mass % sodium hydroxide solution is added to thisin small increments while sufficiently stirring, and this is left tostand for 2 hours. The pulp is filtered, and the pulp on the filterpaper is washed with ion-exchanged water. The endpoint of washing isdefined as the point when the pH of the filtrate reaches 8.5 or lower.

The entire amount of pulp on the filter paper is transferred to a 100 mLscrew vial, and in order to measure the water content in the sample, themass of the pulp at this time is precisely measured and recorded. Next,100 g of a 0.05 N hydrochloric acid solution is added to the preciselymeasured pulp, and a lid is placed on the screw vial. After the solutionis vigorously shaken and mixed, the solution is left to stand for 1hour.

Using a glass filter that has been sufficiently dried, the slurry in thescrew vial is filtered, and the filtrate is collected on a receptacle.After 3 g of the obtained filtrate is transferred to a 100 mL beaker, 2or 3 drops of a methyl red indicator are added, and titration isperformed with a 0.01 N sodium hydroxide solution. The sodium hydroxidesolution is dropped into the solution, and the endpoint of titration isdetermined as the point when the color of the solution changes from theoriginal pink color to orange and yellow.

The amount of cationic groups that are introduced is calculated inaccordance with the calculation formulation shown in Formula 1. Theblank value of titration is determined by the titration of 3 g of a 0.05N hydrochloric acid solution.

$\begin{matrix}{{\left( {{Substituent}\mspace{14mu} {amount}} \right)\left\lbrack {{mmol}\text{/}g} \right\rbrack} = {{{\left\{ {\left( {V_{0} \times C_{NaOH} \times \frac{W_{HCl}}{W_{0}}} \right) - \; \left( {V_{0} \times C_{NaOH} \times \frac{W_{HCl} + W_{water}}{W_{sample}}} \right)} \right\}/W_{{BD}\text{-}{pulp}}}/N} = {\left\{ {\left( {V_{0} \times \frac{W_{HCl}}{W_{0}}} \right) - \left( {V \times \frac{W_{HCl} + W_{water}}{W_{sample}}} \right)} \right\} \frac{C_{NaOH}}{W_{{BD}\text{-}{pulp}}N}}}} & \left\lbrack {{Formula}\mspace{14mu} 1} \right\rbrack\end{matrix}$

V₀: blank titration amount, C_(NaOH): sodium hydroxide solutionconcentration, W_(HCl): amount of hydrochloric acid added to the sample,W₀: amount of blank hydrochloric acid collected, V: titration amount ofthe sample, W_(sample): amount of the sample filtrate collected,W_(water): water content in the sample, W_(BD-pulp): absolute dry massof the sample, N: valence of the substituents

<Liquid Compound>

The liquid compound contained in the microfibrous cellulose aggregate isa dispersion medium (first dispersion medium) used when manufacturingthe microfibrous cellulose. In addition, the liquid compound is adispersion medium (second dispersion medium) used when remanufacturingthe microfibrous cellulose. The liquid compound contained in themicrofibrous cellulose aggregate is composed of at least one of water oran organic solvent.

Water alone is preferably used as the liquid compound from theperspective of handleability or cost, but an organic solvent may be usedin combination with water, or an organic solvent may be used alone.Preferable organic solvents are polar solvents such as alcohol solvents(methanol, ethanol, propanol, butanol, or the like), ketone solvents(acetone, methyl ethyl ketone, or the like), ether solvents (diethylether, ethylene glycol dimethyl ether, tetrahydrofuran, or the like),and acetate solvents (ethyl acetate or the like).

The content of the liquid compound in the microfibrous celluloseaggregate is above 15 mass %, preferably above 50 mass %, and morepreferably above 70 mass % with per the mass of the entire microfibrouscellulose aggregate. When the content of the liquid compound is lessthan the lower limit described above, the redispersibility of themicrofibrous cellulose may decrease.

The content of the liquid compound is preferably at most 94 mass % withrespect to the mass of the entire microfibrous cellulose aggregate.

<Flocculant Containing a Salt of a Polyvalent Metal>

The microfibrous cellulose aggregate may contain a flocculant containinga salt of a polyvalent metal, which is used in the manufacturing methodof the microfibrous cellulose aggregate described below.

Specific examples of flocculants include aluminum sulfate (sulfuric acidband), aluminum polychloride, calcium chloride, magnesium chloride,potassium chloride, calcium sulfate, magnesium sulfate, potassiumsulfate, lithium phosphate, potassium phosphate, trisodium phosphate,disodium hydrogen phosphate, and the like. One type of these flocculantsmay be contained in the microfibrous cellulose aggregate, or two or moretypes of these flocculants may be contained.

Of the flocculants containing salts of polyvalent metals, aluminumsulfate is preferable when the surface charge of the microfibrouscellulose is negative, and disodium hydrogen phosphate is preferablewhen the surface charge of the microfibrous cellulose is positive fromthe perspective of aggregability and cost.

When a flocculant containing a salt of a polyvalent metal is containedin the microfibrous cellulose aggregate, the content is preferably from0.5 parts by mass to 300 parts by mass, more preferably from 1.0 partsby mass to 50 parts by mass, and even more preferably from 2 parts bymass to 30 parts by mass with respect to 100 parts by mass of themicrofibrous cellulose. The microfibrous cellulose aggregate having aflocculant content of greater than or equal to the lower limit describedabove can be obtained in a short period of time. However, it is futilefor a flocculant to be added in excess of the upper limit describedabove since there will be practically no improvement in theaggregability.

<Acid>

When the surface charge of the microfibrous cellulose is negative (whenthe microfibrous cellulose is anionic), the microfibrous celluloseaggregate may contain an acid used in the manufacturing method of themicrofibrous cellulose aggregate described below. The acid may be eitheran inorganic acid or an organic acid.

Examples of inorganic acids include sulfuric acid, hydrochloric acid,nitric acid, phosphoric acid, and the like.

Examples of organic acids include formic acid, acetic acid, citric acid,malic acid, lactic acid, adipic acid, sebacic acid, stearic acid, maleicacid, succinic acid, tartaric acid, fumaric acid, gluconic acid, and thelike. One type of these acids may be contained in the microfibrouscellulose aggregate, or two or more types of these acids may becontained.

Of these acids, sulfuric acid is preferable from the perspectives ofaggregability and cost.

When an acid is contained in the microfibrous cellulose aggregate, thepH thereof is preferably below 4.0, more preferably below 3.5, and evenmore preferably below 3.2. Here, the pH is the value at 23° C.

A microfibrous cellulose aggregate with a pH lower than or equal to theupper limit described above can be obtained in a short period of time.In addition, as long as the pH of the microfibrous cellulose aggregateis less than or equal to the upper limit described above, it is possibleto improve the redispersibility of the microfibrous cellulose when themicrofibrous cellulose aggregate is redispersed in a dispersion medium.

The pH of the microfibrous cellulose aggregate is preferably at least1.0, more preferably above 1.5, and even more preferably above 2.0. Froma practical standpoint, it is difficult to set the pH of themicrofibrous cellulose aggregate to a level lower than the lower limitdescribed above.

<Cationic Surfactant>

When the surface charge of the microfibrous cellulose is negative (whenthe microfibrous cellulose is anionic), the microfibrous celluloseaggregate may contain a cationic surfactant.

Examples of types of cationic surfactants include quaternary ammoniumsalts such as alkyl trimethyl ammonium salts, dialkyl dimethyl ammoniumsalts, alkyl dimethyl benzyl ammonium salts, acyl amino ethyl diethylammonium salts, acyl amino ethyl diethyl amine salts, alkyl amide propyldimethyl benzyl ammonium salts, alkyl pyridinium salts, alkyl pyridiniumsulfuric acid salts, stearamide methyl pyridinium salts, alkylquinolinium salts, alkyl isoquinolinium salts, fatty acid polyethylenepolyamides, acyl amino ethyl pyridinium salts, and acyl colamino formylmethyl pyridinium salts, ester-bonded amine or ether-bonded quaternaryammonium salts such as stearoxy methyl pyridinium salts, fatty acidtriethanolamine, fatty acid triethanolamine formic acid salts,trioxyethylene fatty acid triethanolamine, cetyloxy methyl pyridiniumsalts, and p-isooctyl phenoxy ethoxy ethyl dimethyl benzyl ammoniumsalts, heterocyclic amines such as alkyl imidazoline,1-hydroxyethyl-2-alkylimidazoline,1-acetylaminoethyl-2-alkylimidazoline, and2-alkyl-4-methyl-4-hydroxymethyloxazoline, and amine derivatives such aspolyoxyethylene alkyl amine, N-alkyl propylene diamine, N-alkylpolyethylene polyamine, N-alkyl polyethylene polyamine dimethyl sulfuricacid salts, alkyl biguanide, and long-chain amine oxide, and the like.One type of these cationic surfactants may be contained in themicrofibrous cellulose aggregate, or two or more types of these cationicsurfactants may be contained.

When a cationic surfactant is contained in the microfibrous celluloseaggregate, the content is preferably from 0.5 parts by mass to 300 partsby mass, more preferably from 1.0 parts by mass to 50 parts by mass, andeven more preferably from 2 parts by mass to 30 parts by mass withrespect to 100 parts by mass of the microfibrous cellulose. Themicrofibrous cellulose aggregate with a surfactant content greater thanor equal to the lower limit described above can be obtained in a shortperiod of time. However, it is futile for a surfactant to be added inexcess of the upper limit described above since there will bepractically no improvement in the aggregability.

<Cationic Polymer Flocculant>

When the surface charge of the microfibrous cellulose is negative (whenthe microfibrous cellulose is anionic), the microfibrous celluloseaggregate may contain a cationic polymer flocculant.

Examples of types of cationic polymer flocculants include copolymerswith cationic monomers such as acrylamide and dialkyl amino alkyl(meth)acrylate, dialkyl amino alkyl (meth)acrylamide, or salts orquaternary compounds thereof, or homopolymers or copolymers of thesecationic monomers. One type of these cationic polymer flocculants may becontained in the microfibrous cellulose aggregate, or two or more typesof these cationic polymer flocculants may be contained.

When a cationic polymer flocculant is contained in the microfibrouscellulose aggregate, the content is preferably from 0.5 parts by mass to300 parts by mass, more preferably from 1.0 parts by mass to 50 parts bymass, and even more preferably from 2 parts by mass to 30 parts by masswith respect to 100 parts by mass of the microfibrous cellulose. Themicrofibrous cellulose aggregate with a polymer flocculant contentgreater than or equal to the lower limit described above can be obtainedin a short period of time. However, it is futile for a polymerflocculant to be added in excess of the upper limit described abovesince there will be practically no improvement in the aggregability.

When the surface charge of the microfibrous cellulose is negative (whenthe microfibrous cellulose is anionic), the microfibrous celluloseaggregate may contain at least one of the aforementioned acids, cationicsurfactants, and cationic polymer flocculants. In addition, in thiscase, the microfibrous cellulose aggregate may further contain aflocculant containing a salt of a polyvalent metal.

<Alkali>

When the surface charge of the microfibrous cellulose is positive (whenthe microfibrous cellulose is cationic), the microfibrous celluloseaggregate may contain an alkali. The alkali may be an inorganic alkalicompound or an organic alkali compound.

Examples of inorganic alkali compounds include lithium hydroxide, sodiumhydroxide, potassium hydroxide, calcium hydroxide, lithium carbonate,lithium hydrogen carbonate, potassium carbonate, potassium hydrogencarbonate, sodium carbonate, sodium hydrogen carbonate, calciumcarbonate, calcium phosphate, calcium hydrogen phosphate, and the like.

Examples of organic alkali compounds include ammonia, hydrazine,methylamine, ethylamine, diethylamine, triethylamine, propylamine,dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane,diaminopentane, diaminohexane, cyclohexylamine, aniline, tetramethylammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammoniumhydroxide, tetrabutyl ammonium hydroxide, benzyl trimethyl ammoniumhydroxide, pyridine, N,N-dimethyl-4-aminopyridine, and the like.

One type of the alkali compounds described above may be used alone, ortwo or more types of the alkali compounds described above may be used incombination. Of these alkalis, sodium hydroxide is preferable from theperspectives of aggregability and cost.

When an alkali is contained in the microfibrous cellulose aggregate, thepH thereof is preferably above 10.0 and more preferably above 12.0.Here, the pH is the value at 23° C. A microfibrous cellulose aggregatewith a pH greater than or equal to the upper limit described above canbe obtained in a short period of time.

The pH of the microfibrous cellulose aggregate is preferably below 14.0and more preferably below 13.0. From a practical standpoint, it isdifficult to set the pH of the microfibrous cellulose aggregate to alevel exceeding the upper limit described above.

<Anionic Surfactant>

When the surface charge of the microfibrous cellulose is positive (whenthe microfibrous cellulose is cationic), the microfibrous celluloseaggregate may contain an anionic surfactant.

Examples of types of anionic surfactants include sodium oleate,potassium oleate, sodium laurate, sodium dodecylbenzene sulfonate,sodium alkylnaphthalene sulfonate, sodium dialkyl sulfosuccinate, sodiumpolyoxyethylene alkyl ether sulfate, sodium polyoxyethlyene alkyl allylether sulfate, sodium polyoxyethylene dialkyl sulfate, polyoxyethylenealkyl ether phosphoric acid ester, polyoxyethylene alkyl allyl etherphosphoric acid ester, and the like. One type of these anionicsurfactants may be contained in the microfibrous cellulose aggregate, ortwo or more types of these anionic surfactants may be contained.

When an anionic surfactant is contained in the microfibrous celluloseaggregate, the content is preferably from 0.5 parts by mass to 300 partsby mass, more preferably from 1.0 parts by mass to 50 parts by mass, andeven more preferably from 2 parts by mass to 30 parts by mass withrespect to 100 parts by mass of the microfibrous cellulose. Themicrofibrous cellulose aggregate with a surfactant content greater thanor equal to the lower limit described above can be obtained in a shortperiod of time. However, it is futile for a surfactant to be added inexcess of the upper limit described above since there will bepractically no improvement in the aggregability.

<Anionic Polymer Flocculant>

When the surface charge of the microfibrous cellulose is positive (whenthe microfibrous cellulose is cationic), the microfibrous celluloseaggregate may contain an anionic polymer flocculant used in themanufacturing method of the microfibrous cellulose-containing substancedescribed below. Examples of types of anionic polymer flocculantsinclude polyacrylic acids, sodium polyacrylate, copolymers of(meth)acrylic acids or alkali metal salts thereof and (meth)acrylamide,poly(meth)acrylamide hydrolysates, acryloylamino-2-methylpropyl sulfonicacid, styrene sulfonic acid, copolymers of vinyl sulfonic acids such asvinyl sulfonic acids or salts thereof and (meth)acrylic acids or alkalimetal salts thereof and (meth)acrylamide, carboxymethylcellulose,carboxymethyl starch, sodium alginate, and the like. One type of theseanionic polymer flocculants may be contained in the microfibrouscellulose aggregate, or two or more types of these anionic polymerflocculants may be contained.

When an anionic polymer flocculant is contained in the microfibrouscellulose aggregate, the content is preferably from 0.5 parts by mass to300 parts by mass, more preferably from 1.0 parts by mass to 50 parts bymass, and even more preferably from 2 parts by mass to 30 parts by masswith respect to 100 parts by mass of the microfibrous cellulose. Themicrofibrous cellulose aggregate with a polymer flocculant contentgreater than or equal to the lower limit described above can be obtainedin a short period of time. However, it is futile for a polymerflocculant to be added in excess of the upper limit described abovesince there will be practically no improvement in the aggregability.

When the surface charge of the microfibrous cellulose is positive (whenthe microfibrous cellulose is cationic), the microfibrous celluloseaggregate may contain at least one of the aforementioned alkalis,anionic surfactants, and anionic polymer flocculants. In addition, inthis case, the microfibrous cellulose aggregate may further contain aflocculant containing a salt of a polyvalent metal.

<Plasticizer>

Regardless of whether the surface charge of the microfibrous celluloseis positive or negative, the microfibrous cellulose aggregate maycontain a cellulose plasticizer. When a plasticizer is contained in themicrofibrous cellulose aggregate, hydrogen bonds between the fibers ofthe microfibrous cellulose can be inhibited in the concentration step.This facilitates dispersion in the redispersion step even after thesolid content concentration is increased at the time of concentration.

Examples of types of plasticizers include polyvalent alcohols such assugar, sugar alcohol, glycerin, ethylene glycol, propanediol,butanediol, butanetriol, cyclobutanediol, butanetetraol,cyclobutanetetraol, pentanediol, cyclopentanediol, pentanetriol,pentanetetraol, cyclopentanetriol, or hydroquinone, aliphatic aminessuch as ethylenediamine, trimethylenediamine, triethylenediamine,tetramethylenediamine, hexamethylenediamine, diethylenetriamine,triethylenetetramine, and tetraethylenepentamine, and urea compoundssuch as urea. Two or more types of these plasticizers may also becontained.

When a plasticizer is contained in the microfibrous cellulose aggregate,the content is preferably from 0.5 parts by mass to 10,000 parts bymass, more preferably from 1.0 parts by mass to 8,000 parts by mass, andeven more preferably from 2 parts by mass to 5,000 parts by mass withrespect to 100 parts by mass of the microfibrous cellulose. Themicrofibrous cellulose aggregate having a plasticizer content greaterthan or equal to the lower limit described above has goodredispersibility after concentration. However, it is futile for aplasticizer to be added in excess of the upper limit described abovesince there will be practically no improvement in the dispersibility atthe time of redispersion.

<Emulsion Resin>

The microfibrous cellulose aggregate may contain an emulsion resin. Whenan emulsion resin is contained in the microfibrous cellulose aggregate,it becomes difficult for aggregates to be formed when an emulsion resinis mixed into a microfibrous cellulose dispersion liquid obtained fromthe microfibrous cellulose aggregate. Therefore, a compound materialcomprising the microfibrous cellulose and an emulsion resin can bemanufactured easily.

Here, an emulsion resin refers to particles of a natural resin orsynthetic resin emulsified in a dispersion medium, the particle sizebeing from 0.001 μm to 10 μm. The type of resin constituting theemulsion resin is not particularly limited, but examples includeprecursors such as polystyrenes, polyvinyl chloride, polyvinylidenechloride, vinyl polyacetate, ethylene-vinyl acetate copolymers,poly(meth)acrylic acid alkyl ester polymers, (meth)acrylic acid alkylester copolymers, poly(meth)acrylonitrile, polyesters, polyurethanes,polyamides, epoxy resins, oxetane resins, phenol resins, urea resins,melamine resins, unsaturated polyester resins, silicon resins, anddiallyl phthalate resins, and resin emulsions such as monomers oroligomers constituting these precursors, natural rubbers,styrene-butadiene copolymers, (meth)acrylonitrile-butadiene copolymers,polyisoprenes, polychloroprenes, styrene-butadiene-methyl methacrylatecopolymers, styrene-(meth)acrylic acid alkyl ester copolymers, and thelike. In addition, the emulsion resin may also be a polyethylene, apolypropylene, a polyurethane, an ethylene-vinyl acetate copolymer, orthe like emulsified by a subsequent emulsion method. Two or more typesof these emulsion resins may also be contained.

<Other Components>

The microfibrous cellulose aggregate may contain preservatives,pigments, UV absorbers, antioxidants, or the like as necessary.

“Method for Manufacturing a Microfibrous Cellulose Aggregate”

The microfibrous cellulose aggregate described above is manufactured bya manufacturing method having a concentration step of concentrating amicrofibrous cellulose dispersion liquid in a slurry form containingmicrofibrous cellulose and a liquid compound as a dispersion medium.

<Microfibrous Cellulose Dispersion Liquid Preparation Method>

The microfibrous cellulose dispersion liquid (first microfibrouscellulose dispersion liquid) used in the concentration step is preparedfrom a microfibrous cellulose raw material (hereafter called a“cellulose raw material”) with a preparation method having a chemicaltreatment step and a fibrillation step.

(Cellulose Raw Material)

The cellulose raw material is a material containing cellulose, examplesof which include pulp for papermaking, cotton pulp such as cottonlinters or cotton lint, non-wood pulp such as hemp, straw, or bagasse,and cellulose isolated from sea squirts, seaweed or the like. Of these,from the perspectives of availability, pulp for papermaking ispreferable. Examples of pulp for papermaking include hardwood kraft pulp(bleached kraft pulp (LBKP), unbleached kraft pulp (LUKP), oxygenbleached kraft pulp (LOKP), and the like); softwood kraft pulp (bleachedkraft pulp (NBKP), unbleached kraft pulp (NUKP), oxygen bleached kraftpulp (NOKP), and the like); chemical pulp such as sulfite pulp (SP) andsoda pulp (AP); semichemical pulp such as semichemical pulp (SCP) andchemiground wood pulp (CGP); mechanical pulp such as groundwood pulp(GP) and thermomechanical pulp (TMP or BCTMP); non-wood pulp in whichthe raw material is paper mulberry, mitsumata, hemp, kenaf, or the like;and deinked pulp in which the raw material is a used paper. Of these,from the perspectives of availability, kraft pulp, deinked pulp, orsulfite pulp is preferable.

One type of the cellulose raw material may be used alone, or two or moretypes of the cellulose raw material may be used in combination.

(Chemical Treatment Step)

The chemical treatment step is a step of performing chemical treatmenton the cellulose raw material. Chemical treatment includes at least onetype from among steps (a) to (g) below.

Step (a) is a treatment step using a carboxylic acid compound. Step (b)is a treatment step using an oxoacid containing phosphorus atoms or asalt thereof. Step (c) is a treatment step using ozone. Step (d) is atreatment step using an enzyme. Step (e) is a treatment step using a2,2,6,6-tetramethylpiperidinooxy radical (hereafter abbreviated as“TEMPO”). Step (I) is a treatment step using sulfuric acid. Step (g) isa cationization agent treatment step.

[Treatment Using a Carboxylic Acid Compound]

In treatment using a carboxylic acid compound, the hydroxy groups of thecellulose molecule and a carboxylic acid compound undergo a dehydrationreaction so as to form a polar group (—COO—). As a result, the bondingstrength between cellulose fibers weakens, and the fibrillationproperties improve.

Examples of methods for treating the cellulose raw material using acarboxylic acid compound include a method of mixing a gasifiedcarboxylic acid compound into the cellulose raw material and a method ofadding a carboxylic acid compound to a dispersion liquid of thecellulose raw material. Of these, the method of mixing a gasifiedcarboxylic acid compound into the cellulose raw material is preferablein that the process is simple and the efficiency of introducing carboxygroups increases. An example of a method for gasifying the carboxylicacid compound is a method of heating the carboxylic acid compound.

The carboxylic acid compound used in this treatment is at least one typeselected from the group consisting of compounds having two carboxygroups, acid anhydrides of compounds having two carboxy groups, andderivatives thereof. Of the compounds having two carboxy groups,compounds having two carboxy groups (dicarboxylic acid compounds) arepreferable.

Examples of compounds having two carboxy groups include dicarboxylicacid compounds such as propanedioic acid (malonic acid), butanedioicacid (succinic acid), pentanedioic acid (glutaric acid), hexanedioicacid (adipic acid), 2-methylpropanedioic acid, 2-methylbutanedioic acid,2-methylpentanedioic acid, 1,2-cyclohexanedicarboxylic acid,2-butenedioic acid (maleic acid, fumaric acid), 2-pentenedioic acid,2,4-hexadienedioic acid, 2-methyl-2-butenedioic acid,2-methyl-2-pentenedioic acid, 2-methylidenebutanedioic acid (itaconicacid), benzene-1,2-dicarboxylic acid (phthalic acid),benzene-1,3-dicarboxylic acid (isophthalic acid),benzene-1,4-dicarboxylic acid (terephthalic acid), and ethanedioic acid(oxalic acid).

Examples of acid anhydrides of compounds having two carboxy groupsinclude maleic anhydride, succinic anhydride, phthalic anhydride,glutaric anhydride, adipic anhydride, itaconic anhydride, pyromelliticanhydride, dicarboxylic acid compounds such as 1,2-cyclohexanedicarboxylic acid anhydride, and acid anhydrides of compounds containinga plurality of carboxy groups.

Examples of derivatives of acid anhydrides of compounds having twocarboxy groups include substances in which at least some of the hydrogenatoms of an acid anhydride of a compound having carboxy groups, such asdimethyl maleic anhydride, diethyl maleic anhydride, and diphenyl maleicanhydride, are substituted with substituents (for example, alkyl groups,phenyl groups, or the like).

Of these, maleic anhydride, succinic anhydride, and phthalic anhydrideare preferable in that they can be easily applied industrially and canbe easily gasified.

The mass ratio of the carboxylic acid compound to the cellulose rawmaterial is preferably such that the amount of the carboxylic acidcompound is from 0.1 parts by mass to 500 parts by mass and morepreferably from 10 parts by mass to 200 parts by mass with respect to100 parts by mass of the cellulose raw material. When the ratio of thecarboxylic acid compound is greater than or equal to the lower limitdescribed above, the yield of the microfibrous cellulose can be furtherimproved. However, when the ratio exceeds the upper limit describedabove, the yield-improving effect hits a ceiling, and the carboxylicacid compound is simply used wastefully.

The apparatus used in this treatment is not particularly limited, but,for example, a heating reaction vessel or a rotary type heating reactionvessel having stirring blades, a pressure vessel or a rotary typepressure vessel having a heating jacket, single-shaft mixers anddouble-shaft mixers having heating jackets, a twin-screw extruder, amulti-screw kneading extruder, or kneading apparatus having a heatingapparatus such as a pressure kneader or a dual arm type kneader may beused.

The treatment temperature is preferably at most 250° C. from theperspective of the thermolysis temperature of cellulose.

Furthermore, when water is contained at the time of treatment, thetemperature is preferably from 80° C. to 200° C. and more preferablyfrom 100° C. to 170° C.

The treatment time is preferably from 10 minutes to 5 hours.

In this treatment, a catalyst may also be used as necessary. A basiccatalyst such as pyridine, triethylamine, sodium hydroxide, or sodiumacetate or an acidic catalyst such as acetic acid, sulfuric acid, orperchloric acid is preferably used as the catalyst.

After treatment using a carboxylic acid compound, it is preferable toperform alkali treatment for treating the cellulose dispersion liquidobtained as a result of the above treatment with an alkali solution.

The method used for alkali treatment is not particularly limited, but anexample is a method of immersing the treated cellulose in an alkalisolution.

The alkali compound contained in the alkali solution may be an inorganicalkali compound or an organic alkali compound. Examples of inorganicalkali compounds include hydroxides of alkali metals or hydroxides ofalkali earth metals, carbonates of alkali metals or carbonates of alkaliearth metals, and phosphates of alkali metals or phosphates of alkaliearth metals. Examples of hydroxides of alkali metals include lithiumhydroxide, sodium hydroxide, and potassium hydroxide, and an example ofa hydroxide of an alkali earth metal is calcium hydroxide.

Examples of carbonates of alkali metals include lithium carbonate,lithium hydrogen carbonate, potassium carbonate, potassium hydrogencarbonate, sodium carbonate, and sodium hydrogen carbonate. An exampleof a carbonate of an alkali earth metal is calcium carbonate.

Examples of phosphates of alkali metals include lithium phosphate,potassium phosphate, trisodium phosphate, disodium hydrogen phosphate,and the like. Examples of phosphates of alkali earth metals includecalcium phosphate, calcium hydrogen phosphate, and the like.

Examples of organic alkali compounds include ammonia, aliphatic amines,aromatic amines, aliphatic ammonium, aromatic ammonium, heterocycliccompounds and hydroxides thereof, carbonates thereof, and phosphatesthereof.

Examples include ammonia, hydrazine, methylamine, ethylamine,diethylamine, triethylamine, propylamine, dipropylamine, butylamine,diaminoethane, diaminopropane, diaminobutane, diaminopentane,diaminohexane, cyclohexylamine, aniline, tetramethyl ammonium hydroxide,tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide,tetrabutyl ammonium hydroxide, benzyl trimethyl ammonium hydroxide,pyridine, N,N-dimethyl-4-aminopyridine, ammonium carbonate, ammoniumhydrogen carbonate, 2-ammonium hydrogen phosphate, and the like.

One type of the alkali compounds described above may be used alone, ortwo or more types of the alkali compounds may be used in combination.

The solvent in the alkali solution may be either water or an organicsolvent, but a polar solvent (water or a polar organic solvent such asalcohol) is preferable, and a water-based solvent containing at leastwater is more preferable.

In addition, of these alkali solutions, a sodium hydroxide aqueoussolution, a potassium hydroxide aqueous solution, and an ammonia aqueoussolution are particularly preferable due to their high versatility.

The pH at 25° C. of the alkali solution in which cellulose is immersedis preferably at least 9, more preferably at least 10, and even morepreferably from 11 to 14. When the pH of the alkali solution is greaterthan or equal to the lower limit described above, the yield of themicrofibrous cellulose becomes even higher. However, when the pH exceeds14, the handleability of the alkali solution decreases.

[Treatment Using an Oxoacid Containing Phosphorus Atoms or a SaltThereof]

In treatment using an oxoacid containing phosphorus atoms (hereaftercalled a “phosphorus oxoacid”) or a salt thereof, the hydroxy groups ofthe cellulose molecule and a phosphorus oxoacid having at least (HPO₄)²⁻or a salt thereof undergo a dehydration reaction so as to form a polargroup (—O—PO₃ ²⁻) as described in the following reaction formula (A). Asa result, the bonding strength between cellulose fibers weakens, and thefibrillation properties improve.

—OH+HPO₄ ²⁻→—O—PO₃ ²⁻+H₂O  (A)

Examples of phosphorus oxoacids include phosphoric acid, metaphosphoricacid, polyphosphoric acid, and the like.

Examples of phosphorus oxoacid salts include lithium salts, sodiumsalts, potassium salts, calcium salts, ammonium salts, and organicalkali salts of phosphoric acid, metaphosphoric acid, and polyphosphoricacid, and the like.

One type of phosphorus oxoacid or a salt thereof may be used alone, ortwo or more types of phosphorus oxoacid or a salt thereof may be used incombination.

Of these, phosphoric acid and/or sodium salts of phosphoric acid andpotassium salts of phosphoric acid are preferable due to their low cost,ease of handling, and high phosphoric acid group introductionefficiency.

The mass ratio of the phosphorus oxoacid or a salt thereof to thecellulose raw material is preferably such that the amount of thephosphorus oxoacid or a salt thereof is, in terms of the phosphoruselement amount, from 0.2 parts by mass to 500 parts by mass, morepreferably from 1 parts by mass to 400 parts by mass, and mostpreferably from 2 parts by mass to 200 parts by mass with respect to 100parts by mass of the cellulose raw material. When the ratio of thephosphorus oxoacid or a salt thereof is greater than or equal to thelower limit described above, the yield of the microfibrous cellulose canbe further improved. However, when the ratio exceeds the upper limitdescribed above, the yield-improving effect hits a ceiling, and thephosphorus oxoacid or a salt thereof is simply used wastefully.

The thermal treatment temperature is preferably at most 250° C. from theperspective of the thermolysis temperature of cellulose. In addition,the thermal treatment temperature is preferably from 100° to 170° C.from the perspective of suppressing the hydrolysis of the cellulose.Furthermore, the heating while water is contained in the system in whichthe phosphorus oxoacid or a salt thereof is added at the time of thermaltreatment is preferably performed at a temperature of at most 130° C.and more preferably at most 110° C. so as to sufficiently remove and drythe water content. It is preferable to perform thermal treatmentthereafter at 100° C. to 170° C. In addition, when removing the watercontent, a vacuum dryer may be used.

The treatment time is preferably from 10 minutes to 5 hours.

After treatment using a phosphorus oxoacid or a salt thereof, alkalitreatment may be performed in the same manner as in the case oftreatment using a carboxylic acid compound.

[Treatment Using Ozone]

In treatment using ozone, some of the hydroxyl groups of cellulose aresubstituted with carbonyl groups or carboxy groups. As a result, thebonding strength between cellulose fibers weakens, and the fibrillationproperties improve.

Ozone can be generated by supplying an oxygen-containing gas such asair, oxygen gas, or oxygen-enriched air to a known ozone-generatingapparatus.

Treatment using ozone is performed by exposing the cellulose rawmaterial to a closed space/atmosphere in which ozone is present.

When the ozone concentration in the gas containing ozone is 250 g/m³ orhigher, there is a risk of explosion, so the concentration must be lessthan 250 g/m³. However, when the concentration is low, the amount ofozone used increases, so the concentration is preferably from 50 g/m³ to215 g/m³. When the ozone concentration is greater than or equal to thelower limit described above, the ozone is easy to handle, and the yieldimproving effect of the microfibrous cellulose becomes even higher inthe fibrillation step.

The amount of ozone added to the cellulose raw material is notparticularly limited, but the amount is preferably from 5 parts by massto 30 parts by mass with respect to 100 parts by mass of the solidcontent of the cellulose raw material. When the amount of ozone added isgreater than or equal to the lower limit described above, the yieldimproving effect of the microfibrous cellulose becomes even higher inthe fibrillation step. However, when the amount exceeds the upper limitdescribed above, this causes a decrease in yield and the deteriorationof dewaterability before and after ozone treatment. In addition, theyield improving effect of the microfibrous cellulose hits a ceiling inthe fibrillation step.

The ozone treatment temperature is not particularly limited and isadjusted appropriately in a range of 0° C. to 50° C. In addition, theozone treatment time is not particularly limited and is adjustedappropriately in a range of 1 minute to 360 minutes.

After ozone treatment is performed on the cellulose raw material,additional oxidation treatment may be performed. Examples of oxidizingagents used in additional oxidation treatment include chlorine-basedcompounds such as chlorine dioxide and sodium chlorite.

After ozone treatment, alkali treatment may be performed in the samemanner as in the case of treatment using a carboxylic acid compound.

[Treatment Using an Enzyme]

In treatment using an enzyme, the cellulose can be decomposed by anenzyme.

The cellulolytic enzyme used in the enzyme treatment is an enzymegenerally termed cellulase having cellobiohydrolase activity,endo-glucanase activity, or beta-glycosidase activity.

The cellulolytic enzyme used in the enzyme treatment may be acommercially available cellulase formulations although the cellulolyticenzyme may be prepared by mixing various cellulolytic enzymes withenzymes each having activity at appropriate amounts. Many ofcommercially available cellulase formulations simultaneously havevarious cellulase activities described above and a hemicellulaseactivity.

Commercially available cellulase formulations include cellulaseformulations derived from the genus Trichoderma, the genus Acremonium,the genus Aspergillus, the genus Phanerochaete, the genus Trametes, thegenus Humicola, the genus Bacillus, and the like. Examples of suchcommercially available cellulase formulations include Cell Leucine T2(manufactured by HBI Enzymes Inc.), Meicelase (manufactured by MeijiSeika Kaisha, Limited), Novozyme 188 (manufactured by Novozymes),Multifect CX10L (manufactured by Genencor), and the like (all mentionedin trade names).

In the enzyme treatment, in addition to cellulase, hemicellulase enzymemay also be used alone or in combination as the enzyme. Among thehemicellulase enzymes, xylanase which is an enzyme decomposing xylan,mannase which is an enzyme decomposing mannan, and arabanase which is anenzyme decomposing araban are preferably used. Pectinase which is anenzyme decomposing pectin can be also used as hemicellulase enzyme.

pH of the dispersion liquid in the enzyme treatment is preferablymaintained in a range in which the activity of the used enzyme will behigh. For example, in the case of a commercially available enzymederived from Trichoderma, pH is preferably from 4 to 8.

The temperature of the dispersion liquid in the enzyme treatment ispreferably maintained in a range in which the activity of the usedenzyme will be high. For example, in the case of a commerciallyavailable enzyme derived from Trichoderma, the temperature is preferablyfrom 40° C. to 60° C. When the temperature is lower than the lower limitdescribed above, the enzyme activity decreases and the treatment timebecomes longer, whereas when the temperature exceeds the upper limitdescribed above, the enzyme may be deactivated.

The treatment time of enzyme treatment is preferably in a range of 10minutes to 24 hours. In the case where the treating time is less than 10minutes, it is difficult for the effect of the enzyme treatment to beexhibited. In the case where the treating time exceeds 24 hours,decomposition by the enzyme of the cellulose fiber proceeds excessivelyand the average fiber length of the obtained fine fiber may be tooshort.

Since if active enzymes remain in an active state after a prescribedtime period, the cellulose decomposition proceeds excessively asdescribed above, so when the prescribed enzyme treatment ends, aterminating treatment for the enzyme reaction is preferably performed.Examples of the terminating treatment for the enzyme reaction include amethod in which the dispersion liquid that has undergone the enzymetreatment is washed with water to remove the enzyme, a method in whichsodium hydroxide is added to the dispersion liquid that has undergonethe enzyme treatment in a manner such that the pH becomes approximately12 to deactivate the enzyme, and a method in which the temperature ofthe dispersion liquid that has undergone the enzyme treatment isincreased to a temperature of 90° C. to deactivate the enzyme.

[Treatment Using TEMPO]

In treatment using TEMPO, an oxidizing agent is reacted with thecellulose raw material in the presence of TEMPO and an alkali halide soas to replace some of the hydroxyl groups of the cellulose with carboxygroups (chemical modification). As a result, the bonding strengthbetween cellulose fibers weakens, and the fibrillation propertiesimprove.

The alkali halide used as an oxidation catalyst together with TEMPO isnot particularly limited, and an alkali iodide, alkali bromide, alkalichloride, alkali fluoride, or the like can be selected appropriately andused.

The oxidizing agent is also not particularly limited, and sodiumhypochlorite, sodium chlorite, sodium hypobromite, sodium bromite, orthe like can be appropriately selected and used.

The amounts of TEMPO and the alkali halide that are used are notparticularly limited but are each preferably from 0.1 parts by mass to15 parts by mass with respect to 100 parts by mass of the solid contentof the cellulose raw material. When the added amounts of TEMPO and thealkali halide are respectively greater than or equal to the lower limitdescribed above, the yield improving effect of the microfibrouscellulose becomes even higher in the fibrillation step. However, whenthe amounts exceed the upper limit described above, there is a risk thatthe yield improving effect of the microfibrous cellulose may hit aceiling in the fibrillation step.

The amount of the oxidizing agent that is used is also not particularlylimited but is preferably from 1 part by mass to 80 parts by mass withrespect to 100 parts by mass of the solid content of the cellulose rawmaterial.

The pH of the dispersion liquid when the dispersion liquid containingthe cellulose raw material is treated with TEMPO is adjustedappropriately in accordance with the type of oxidizing agent that isused. The pH of the cellulose raw material dispersion liquid is adjustedby appropriately adding a basic substance such as potassium hydroxide orammonia or an acidic substance such as acetic acid or oxalic acid.

The treatment temperature when the cellulose raw material is treatedwith TEMPO is preferably in a range of 20° C. to 100° C., and thetreatment time is preferably from 0.5 hours to 4 hours.

In addition, in order to perform treatment using TEMPO uniformly, it ispreferable to perform treatment while stirring with various types ofstirring devices.

[Treatment Using Sulfuric Acid]

Treatment using sulfuric acid is specifically treatment in which thecellulose raw material is added to a sulfuric acid aqueous solution andheated. Hydrolysis occurs as a result of treating the cellulose withsulfuric acid.

The concentration of the sulfuric acid aqueous solution is preferablyfrom 0.01 mass % to 20 mass % and more preferably from 0.1 mass % to 10mass %. When the concentration of the sulfuric acid aqueous solution isgreater than or equal to the lower limit described above, the cellulosecan be sufficiently decomposed, and when the concentration is lower thanor equal to the upper limit described above, the substance has excellenthandleability.

The heating temperature in the sulfuric acid treatment is preferablyfrom 10° C. to 120° C. and more preferably from 20° C. to 80° C. Whenthe heating temperature is greater than or equal to the lower limitdescribed above, the decomposition reaction of cellulose can be easilycontrolled. To prevent water loss from the sulfuric acid aqueoussolution, the vaporized water content is preferably condensed andrefluxed during the heating.

The treatment time is preferably from 10 minutes to 5 hours.

[Cationization Agent Treatment]

Cationization agent treatment uses a cationization agent having aquaternary ammonium group and a group that reacts with the hydroxylgroups of the cellulose. Specific examples of cationization agentsinclude glycidyl trialkyl ammonium halides such as glycidyl trimethylammonium chloride or 3-chloro-2-hydroxypropyl trimethyl ammoniumchloride, or halohydrin forms thereof.

By reacting the cationization agent in the presence of an alkalihydroxide metal (sodium hydroxide, potassium hydroxide, or the like)serving as a catalyst, the cellulose is cationized, and the electricalrepulsion between cations strengthens. As a result, the bonding strengthbetween cellulose fibers weakens, and the fibrillation propertiesimprove.

The amount of the cationization agent that is used is not particularlylimited but is preferably from 10 parts by mass to 1000 parts by masswith respect to 100 parts by mass of the solid content of the celluloseraw material. When the amount of the cationization agent that is used isgreater than or equal to the lower limit described above, the yieldimproving effect of the microfibrous cellulose becomes even higher inthe fibrillation step. However, when the amounts exceed the upper limitdescribed above, the yield improving effect of the microfibrouscellulose may hit a ceiling in the fibrillation step.

The treatment temperature in cationization agent treatment is preferablyin a range of 30° C. and 90° C., and the treatment time is preferablyfrom 1 hour to 3 hours.

(Fibrillation Step)

The fibrillation step is a step of obtaining a microfibrous cellulosedispersion liquid containing microfibrous cellulose by micronizing andfibrillating cellulose treated in the chemical treatment step in adispersion medium (liquid compound, first dispersion medium).

The cellulose prior to micronization is preferably diluted with adispersion medium to form a dispersion liquid having a cellulose contentof 0.1 mass % to 1.0 mass % with respect to the microfibrous cellulosedispersion liquid. The cellulose content is more preferably from 0.2mass % to 5 mass % and even more preferably from 0.3 mass % to 3 mass %per to the microfibrous cellulose dispersion liquid. When the cellulosecontent is greater than or equal to the lower limit described above, thefibrillation efficiency is high, and when the content is less than orequal to the upper limit described above, it is possible to preventincreases in viscosity during the fibrillation treatment.

Examples of the micronizing method include a method of using variouspulverizing apparatuses. As a pulverizing apparatus, a high speedfibrillating device, grinder (stone mill type grinder), high-pressurehomogenizer or ultra high-pressure homogenizer, high pressure collisiontype pulverizer, ball mill, bead mill, disk type refiner, conicalrefiner, twin screw kneader, oscillating mill, homomixer using highspeed rotation, ultrasonic wave disperser, or apparatus for wet grindingsuch as a beater can be appropriately used. Of these, a high-pressurehomogenizer, a high speed rotation type fibrillating device, or thecombined use thereof is particularly preferable.

The microfibrous cellulose dispersion liquid obtained by micronizationas described above may be used directly in the concentration step.Alternatively, after the microfibrous cellulose dispersion liquid iscentrifuged, the supernatant liquid of the microfibrous cellulosedispersion liquid may be collected, and the supernatant liquid may beused in the concentration step. The fiber width tends to be narrow inthe microfibrous cellulose contained in the supernatant liquid.

<Concentration Step>

Examples of concentration methods in the concentration step include amethod having a flocculation step and a filtration step (hereaftercalled a “first concentration method”) and a method having a heatingstep (hereafter called a “second concentration method”). The firstconcentration method is preferable in that a microfibrous celluloseaggregate with high redispersibility can be obtained easily.

The microfibrous cellulose content of the microfibrous cellulosedispersion liquid used in the concentration step is preferably less than6 mass % and more preferably at most 3.0 mass % per the microfibrouscellulose dispersion liquid from the perspective of dispersionstability. The microfibrous cellulose content of the microfibrouscellulose dispersion liquid used in the concentration step is preferablyat least 0.2 mass % and more preferably at least 0.5 mass % per themicrofibrous cellulose dispersion liquid from the perspective of theproductivity of the microfibrous cellulose aggregate.

In addition, in the concentration step, the content of microfibrouscellulose in the microfibrous cellulose aggregate that is obtained ispreferably set to from 6 mass % to 80 mass %, more preferably from 10mass % to 50 mass %, and even more preferably from 12 mass % to 30 mass% per the microfibrous cellulose dispersion liquid. By setting thecontent of microfibrous cellulose with respect to the microfibrouscellulose dispersion liquid after concentration to at least the lowerlimit described above, it is possible to further reduce the shippingcost and the storage cost, and when the content is less than or equal tothe upper limit described above, a microfibrous cellulose aggregate canbe manufactured easily and in a short period of time.

(First Concentration Method)

The first concentration method is a method having a flocculation stepand a filtration step. The flocculation step in the first concentrationmethod is a step of flocculating the microfibrous cellulose contained inthe microfibrous cellulose dispersion liquid described above.

An example of a method for flocculating microfibrous cellulose is amethod in which, when the surface charge of the microfibrous celluloseis negative, at least one type of a flocculant containing a salt of apolyvalent metal, a cationic surfactant, a cationic polymer flocculant,or an acid is added to the microfibrous cellulose dispersion liquid.Another example is a method in which, when the surface charge of themicrofibrous cellulose is positive, at least one type of a flocculantcontaining a salt of a polyvalent metal, an anionic surfactant, ananionic polymer flocculant, or an alkali is added to the microfibrouscellulose dispersion liquid.

Specific examples of flocculants containing salts of polyvalent metalsadded to the microfibrous cellulose dispersion liquid include aluminumsulfate (sulfuric acid band), aluminum polychloride, calcium chloride,magnesium chloride, potassium chloride, calcium sulfate, magnesiumsulfate, potassium sulfate, lithium phosphate, potassium phosphate,trisodium phosphate, disodium hydrogen phosphate, and the like. One typeof these flocculants may be contained in the microfibrous celluloseaggregate, or two or more types of these flocculants may be contained.

Of these flocculants, aluminum sulfate is preferable when the surfacecharge of the microfibrous cellulose is negative, and disodium hydrogenphosphate is preferable when the surface charge of the microfibrouscellulose is positive from the perspectives of aggregability and cost.

When a flocculant containing a salt of a polyvalent metal is added, theadded amount is preferably from 0.5 parts by mass to 300 parts by mass,more preferably from 1.0 parts by mass to 50 parts by mass, and evenmore preferably from 2 parts by mass to 30 parts by mass with respect to100 parts by mass of the microfibrous cellulose. When the amount of theflocculant added is greater than or equal to the lower limit describedabove, the microfibrous cellulose can be flocculated easily. However, itis futile for a flocculant to be added in excess of the upper limitdescribed above since there will be practically no improvement in theaggregability.

Examples of cationic surfactants to be added to the microfibrouscellulose dispersion liquid include quaternary ammonium salts such asalkyl trimethyl ammonium salts, dialkyl dimethyl ammonium salts, alkyldimethyl benzyl ammonium salts, acyl amino ethyl diethyl ammonium salts,acyl amino ethyl diethyl amine salts, alkyl amide propyl dimethyl benzylammonium salts, alkyl pyridinium salts, alkyl pyridinium sulfuric acidsalts, stearamide methyl pyridinium salts, alkyl quinolinium salts,alkyl isoquinolinium salts, fatty acid polyethylene polyamides, acylamino ethyl pyridinium salts, and acyl colamino formyl methyl pyridiniumsalts, ester-bonded amine or ether-bonded quaternary ammonium salts suchas stearoxy methyl pyridinium salts, fatty acid triethanolamine, fattyacid triethanolamine formic acid salts, trioxyethylene fatty acidtriethanolamine, cetyloxy methyl pyridinium salts, and p-isooctylphenoxy ethoxy ethyl dimethyl benzyl ammonium salts, heterocyclic aminessuch as alkyl imidazoline, 1-hydroxyethyl-2-alkylimidazoline,1-acetylaminoethyl-2-alkylimidazoline, and2-alkyl-4-methyl-4-hydroxymethyloxazoline, amine derivatives such aspolyoxyethylene alkyl amine, N-alkyl propylene diamine, N-alkylpolyethylene polyamine, N-alkyl polyethylene polyamine dimethyl sulfuricacid salts, alkyl biguanide, and long-chain amine oxide, and the like.

One type of these cationic surfactants may be contained in themicrofibrous cellulose aggregate, or two or more types may be contained.

Examples of cationic polymer flocculants to be added to the microfibrouscellulose dispersion liquid include copolymers with cationic monomerssuch as acrylamide and dialkyl amino alkyl (meth)acrylate, dialkyl aminoalkyl (meth)acrylamide, or salts or quaternary compounds thereof, orhomopolymers or copolymers of these cationic monomers. One type of thesecationic polymer flocculants may be contained in the microfibrouscellulose aggregate, or two or more types may be contained.

When cationic surfactant and a cationic polymer flocculant is added, theadded amount is preferably from 0.5 parts by mass to 300 parts by mass,more preferably from 1.0 parts by mass to 50 parts by mass, and evenmore preferably from 2 parts by mass to 30 parts by mass with respect to100 parts by mass of the microfibrous cellulose. With the microfibrouscellulose dispersion liquid having a surfactant content greater than orequal to the lower limit described above, the microfibrous cellulose canbe easily flocculated, and the filtration time can be reduced, whichmakes it possible to obtain a microfibrous cellulose-containing solutionin a short period of time. However, it is futile for a surfactant to beadded in excess of the upper limit described above since there will bepractically no improvement in the aggregability.

The acid added to the microfibrous cellulose dispersion liquid may beeither an inorganic acid or an organic acid. Examples of inorganic acidsinclude sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid,and the like. Examples of organic acids include formic acid, aceticacid, citric acid, malic acid, lactic acid, adipic acid, sebacic acid,stearic acid, maleic acid, succinic acid, tartaric acid, fumaric acid,gluconic acid, and the like. One type of these acids may be contained inthe microfibrous cellulose aggregate, or two or more types of theseacids may be contained.

Of these acids, sulfuric acid is preferable from the perspectives ofaggregability and cost.

When an acid is added, the pH of the obtained microfibrous celluloseaggregate is preferably below 4.0 and more preferably below 3.0. When anacid is added so that the pH is lower than or equal to the upper limitdescribed above, negatively charged microfibrous cellulose can beflocculated easily, which makes it possible to reduce the filtrationtime and to obtain a microfibrous cellulose-containing solution in ashort period of time. However, when the added amount of the acid issmall and the pH exceeds the upper limit described above, theflocculation of negatively charged microfibrous cellulose becomes weak,and it becomes difficult to remove the dispersion medium at the time offiltration in the next step.

The pH of the microfibrous cellulose aggregate is preferably set toabove 1.0 and more preferably set to above 1.5. From a practicalstandpoint, it is difficult to set the pH of the microfibrous celluloseaggregate to a level lower than the lower limit described above.

In addition, the acid may be added to the microfibrous cellulosedispersion liquid together with the flocculants containing salts ofpolyvalent metals, cationic surfactants, and cationic polymers describedabove.

Examples of anionic surfactants to be added to the microfibrouscellulose dispersion liquid include sodium oleate, potassium oleate,sodium laurate, sodium dodecylbenzene sulfonate, sodium alkylnaphthalenesulfonate, sodium dialkyl sulfosuccinate, sodium polyoxyethylene alkylether sulfate, sodium polyoxyethlyene alkyl allyl ether sulfate, sodiumpolyoxyethylene dialkyl sulfate, polyoxyethylene alkyl ether phosphoricacid ester, polyoxyethylene alkyl allyl ether phosphoric acid ester, andthe like.

One type of these anionic surfactants may be contained in themicrofibrous cellulose aggregate, or two or more types of these anionicsurfactants may be contained.

Examples of anionic polymer flocculants to be added to the microfibrouscellulose dispersion liquid include polyacrylic acids, sodiumpolyacrylate, copolymers of (meth)acrylic acids or alkali metal saltsthereof and (meth)acrylamide, poly(meth)acrylamide hydrolysates,acryloylamino-2-methylpropyl sulfonic acid, styrene sulfonic acid,copolymers of vinyl sulfonic acids such as vinyl sulfonic acids or saltsthereof and (meth)acrylic acids or alkali metal salts thereof and(meth)acrylamide, carboxymethylcellulose, carboxymethyl starch, sodiumalginate, and the like. One type of these anionic polymer flocculantsmay be contained in the microfibrous cellulose aggregate, or two or moretypes may be contained.

When an anionic surfactant and an anionic polymer flocculant are added,the added amount is preferably from 0.5 parts by mass to 300 parts bymass, more preferably from 1.0 parts by mass to 50 parts by mass, andeven more preferably from 2 parts by mass to 30 parts by mass withrespect to 100 parts by mass of the microfibrous cellulose. Themicrofibrous cellulose dispersion liquid having a polymer flocculantcontent greater than or equal to the lower limit described above can beeasily flocculated in microfibrous cellulose, and the filtration timecan be reduced, which makes it possible to obtain a microfibrouscellulose-containing solution in a short period of time. However, it isfutile for a polymer flocculant to be added in excess of the upper limitdescribed above since there will be practically no improvement in theaggregability.

The alkali added to the microfibrous cellulose dispersion liquid may bean inorganic alkali compound or an organic alkali compound.

Examples of inorganic alkali compounds include lithium hydroxide, sodiumhydroxide, potassium hydroxide, calcium hydroxide, lithium carbonate,lithium hydrogen carbonate, potassium carbonate, potassium hydrogencarbonate, sodium carbonate, sodium hydrogen carbonate, calciumcarbonate, calcium phosphate, calcium hydrogen phosphate, and the like.

Examples of organic alkali compounds include ammonia, hydrazine,methylamine, ethylamine, diethylamine, triethylamine, propylamine,dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane,diaminopentane, diaminohexane, cyclohexylamine, aniline, tetramethylammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammoniumhydroxide, tetrabutyl ammonium hydroxide, benzyl trimethyl ammoniumhydroxide, pyridine, N,N-dimethyl-4-aminopyridine, and the like.

One type of the alkali compounds described above may be used alone, ortwo or more types of the alkali compounds described above may be used incombination. Of these alkalis, sodium hydroxide is preferable from theperspectives of aggregability and cost.

When an alkali is added, the pH of the microfibrous cellulose aggregateis preferably above 10.0 and more preferably above 12.0. When an alkaliis added so that the pH is greater than or equal to the lower limitdescribed above, positively charged microfibrous cellulose can beflocculated easily, which makes it possible to reduce the filtrationtime and to obtain a microfibrous cellulose-containing solution in ashort period of time. However, when the added amount of the alkali issmall and the pH is less than the lower limit described above, theflocculation of positively charged microfibrous cellulose becomes weak,and it becomes difficult to remove the dispersion medium at the time offiltration in the next step.

The pH of the microfibrous cellulose aggregate is preferably below 14.0and more preferably below 13.0. From a practical standpoint, it isdifficult to set the pH of the microfibrous cellulose aggregate to alevel exceeding the upper limit described above.

In addition, the alkali may be added to the microfibrous cellulosedispersion liquid together with the flocculants containing salts ofpolyvalent metals, anionic surfactants, and anionic polymer flocculantsdescribed above.

When a cellulose plasticizer is added, examples of plasticizers to beadded to the microfibrous cellulose dispersion liquid include polyvalentalcohols such as sugar, sugar alcohol, glycerin, ethylene glycol,propanediol, butanediol, butanetriol, cyclobutanediol, butanetetraol,cyclobutanetetraol, pentanediol, cyclopentanediol, pentanetriol,pentanetetraol, cyclopentanetriol, or hydroquinone, aliphatic aminessuch as ethylenediamine, trimethylenediamine, triethylenediamine,tetramethylenediamine, hexamethylenediamine, diethylenetriamine,triethylenetetramine, and tetraethylenepentamine, and urea compoundssuch as urea. Two or more types of these plasticizers may also becontained.

When a plasticizer is added, the content is preferably from 0.5 parts bymass to 10,000 parts by mass, more preferably from 1.0 parts by mass to8,000 parts by mass, and even more preferably from 2 parts by mass to5,000 parts by mass with respect to 100 parts by mass of themicrofibrous cellulose. The microfibrous cellulose dispersion liquidhaving an additive content greater than or equal to the lower limitdescribed above has good redispersibility after concentration. However,it is futile for a plasticizer to be added in excess of the upper limitdescribed above since there will be practically no improvement in thedispersibility at the time of redispersion.

When the surface charge of the microfibrous cellulose is negative, acellulose plasticizer may be added to the microfibrous cellulosedispersion liquid together with at least one type of flocculantcontaining a salt of a polyvalent metal, an acid, a cationic surfactant,or a cationic polymer flocculant as described above. When the surfacecharge of the microfibrous cellulose is positive, a celluloseplasticizer may be added to the microfibrous cellulose dispersion liquidtogether with at least one type of flocculant containing a salt of apolyvalent metal, an alkali, an anionic surfactant, or an anionicpolymer flocculant as described above.

The filtration step in the first concentration method is a step ofremoving the dispersion medium by filtering the microfibrous cellulosedispersion liquid after the flocculation step. It is not necessary forthe dispersion medium to be removed completely as long as some of thedispersion medium is removed.

As a filtration method in the filtration step, a publicly knownfiltration method using a filter material such as filter paper, filtercloth, or a resin filter may be applied.

The aperture size of the filter material is preferably from 100 nm to3,000 nm and more preferably from 200 nm to 1,000 nm from theperspectives of the separability of the dispersion medium and thefiltration time.

(Second Concentration Method)

The heating step in the second concentration method is a step forheating the microfibrous cellulose dispersion liquid so as to evaporateand remove the dispersion medium.

Examples of heating methods include a method of filling a containerhaving an open top with the microfibrous cellulose dispersion liquid andheating the container, a method of heating a spout with an open top andpouring the microfibrous cellulose dispersion liquid into the spout, amethod of directly heating the microfibrous cellulose dispersion liquid,and the like.

The heating temperature is preferably from 40° C. to 120° C. and morepreferably from 60° C. to 105° C. When the heating temperature isgreater than or equal to the lower limit described above, the dispersionmedium can be evaporated rapidly, and when the heating temperature islower than or equal to the upper limit described above, it is possibleto suppress the cost required for heating and to suppress thedecomposition of cellulose due to heat.

“Method for Remanufacturing a Microfibrous Cellulose Dispersion Liquid”

The microfibrous cellulose dispersion liquid (second microfibrouscellulose dispersion liquid) can be remanufactured using themicrofibrous cellulose aggregate described above.

That is, the method for remanufacturing the microfibrous cellulosedispersion liquid has a redispersion step of preparing a microfibrouscellulose-containing solution by adding a dispersion medium (seconddispersion medium) to the microfibrous cellulose aggregate andperforming dispersion treatment on the microfibrous cellulose-containingsolution.

In other words, remanufacturing the microfibrous cellulose dispersionliquid refers to a method for manufacturing a microfibrous cellulosedispersion liquid having a redispersion step comprising a step ofpreparing a microfibrous cellulose-containing solution by adding adispersion medium to the microfibrous cellulose aggregate describedabove and a step of dispersing the microfibrous cellulose in themicrofibrous cellulose-containing solution.

The same dispersion medium as the liquid compound contained in themicrofibrous cellulose aggregate can be used as the dispersion medium tobe added to the microfibrous cellulose aggregate in the step ofpreparing a microfibrous cellulose-containing solution. However, it isunnecessary for the dispersion medium to be the same as the liquidcompound.

In the step of preparing a microfibrous cellulose-containing solution inthe redispersion step, the microfibrous cellulose content of themicrofibrous cellulose-containing solution is preferably set to from 0.1mass % to 10 mass % and more preferably from 0.2 mass % to 3 mass % perthe microfibrous cellulose-containing solution. When the microfibrouscellulose content of the microfibrous cellulose-containing solution isgreater than or equal to the lower limit described above, the dispersionstability of the microfibrous cellulose becomes higher, and when thecontent is less than or equal to the upper limit described above, theviscosity of the microfibrous cellulose does not become too high, andthe microfibrous cellulose becomes relatively easy to handle.

The microfibrous cellulose content of the microfibrouscellulose-containing solution can be adjusted by the amount of thedispersion medium that is added, and the microfibrous cellulose contentbecomes lower when the added amount of the dispersion medium is greater.

In addition, the redispersibility becomes higher in the redispersionstep, so when the surface charge of the microfibrous cellulose isnegative, it is preferable to add an alkali to the microfibrouscellulose-containing solution. When the surface charge of themicrofibrous cellulose is positive, it is preferable to add an acid.

The alkali added in the redispersion step is the same as the alkali usedin alkali treatment in the concentration step described above. Inaddition, the acid is also the same as the acid used in theconcentration step described above.

The acid or alkali may be added to the microfibrous cellulose-containingsolution while stirring the microfibrous cellulose-containing solution.

When the surface charge of the microfibrous cellulose is negative, thepH (23° C.) of the microfibrous cellulose-containing solution ispreferably set to above 7 and below 12, more preferably above 9 andbelow 12, and even more preferably above 11 and below 12 by adding analkali. When the pH of the microfibrous cellulose dispersion liquid isgreater than or equal to the lower limit described above, theredispersibility of the microfibrous cellulose becomes even higher.

When the surface charge of the microfibrous cellulose is positive, it ispreferable to set the pH (23° C.) of the microfibrouscellulose-containing solution to a range of 4 to 7 by adding an acid.When the pH is within the range described above, the redispersibility ofthe microfibrous cellulose becomes even higher.

The same apparatus as the pulverization apparatus used in thefibrillation step described above, for example, can be used as thedispersion apparatus used in dispersion treatment. One type ofpulverization apparatus may be used alone, or two or more types ofpulverization apparatuses may be used in combination. When two or moretypes of the dispersion apparatuses are used in combination, each may beused sequentially, or the apparatuses may be used simultaneously.

It is preferable to use an ultrasonic disperser as the dispersionapparatus from the perspective that the microfibrous cellulose can alsobe easily redispersed in a microfibrous cellulose-containing solutionhaving a high microfibrous cellulose content.

In the step of dispersing the microfibrous cellulose in the redispersionstep, the microfibrous cellulose content of the microfibrous cellulosedispersion liquid is preferably set to from 0.1 mass % to 10 mass % andmore preferably from 0.2 mass % to 3 mass % per the microfibrouscellulose dispersion liquid. When the microfibrous cellulose content ofthe microfibrous cellulose dispersion liquid is greater than or equal tothe lower limit described above, the dispersion stability of themicrofibrous cellulose becomes higher, and when the content is less thanor equal to the upper limit described above, the viscosity of themicrofibrous cellulose does not become too high, and the microfibrouscellulose becomes relatively easy to handle.

The microfibrous cellulose content of the microfibrous cellulosedispersion liquid can be adjusted by the amount of the dispersion mediumthat is added, and the microfibrous cellulose content becomes lower whenthe added amount of the dispersion medium is greater.

In the remanufacturing method described above, the dispersion treatmentconditions and the alkali or acid addition conditions are selected sothat the ratio (B/A) of the average fiber width B of the microfibrouscellulose contained in the remanufactured microfibrous cellulosedispersion liquid and the average fiber width A of the microfibrouscellulose contained in the microfibrous cellulose dispersion liquid usedin the concentration step described above is preferably from 0.5 to 2.0and more preferably from 0.5 to 1.0. When B/A is within the rangedescribed above, the average fiber width of the microfibrous cellulosecontained in the remanufactured microfibrous cellulose dispersion liquidis roughly the same or narrower than the fiber width of the microfibrouscellulose contained in the microfibrous cellulose dispersion liquid usedin the concentration step. Therefore, the microfibrous cellulosecontained in the remanufactured microfibrous cellulose dispersion liquideasily achieves the properties of the original microfibrous cellulose(high strength, high rigidity, high dimensional stability, highdispersibility when conjugated with a resin, and transparency).

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,an acid, and a cellulose plasticizer, the microfibrous cellulose contentbeing from 6 mass % to 80 mass % and the liquid compound content beingat least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,an inorganic acid, and a cellulose plasticizer, the microfibrouscellulose content being from 6 mass % to 80 mass % and the liquidcompound content being at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,a cationic surfactant, and a cellulose plasticizer, the microfibrouscellulose content being from 6 mass % to 80 mass % and the liquidcompound content being at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,a dialkyl dimethyl ammonium salt, and a cellulose plasticizer, themicrofibrous cellulose content being from 6 mass % to 80 mass % and theliquid compound content being at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,a cationic polymer flocculant, and a cellulose plasticizer, themicrofibrous cellulose content being from 6 mass % to 80 mass % and theliquid compound content being at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,a flocculant containing a salt of a polyvalent metal, an acid, and acellulose plasticizer, the microfibrous cellulose content being from 6mass % to 80 mass % and the liquid compound content being at least 15mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,a flocculant containing a salt of a polyvalent metal, an inorganic acid,and a cellulose plasticizer, the microfibrous cellulose content beingfrom 6 mass % to 80 mass % and the liquid compound content being atleast 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,aluminum sulfate, an acid, and a cellulose plasticizer, the microfibrouscellulose content being from 6 mass % to 80 mass % and the liquidcompound content being at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,a flocculant containing a salt of a polyvalent metal, a cationicsurfactant, and a cellulose plasticizer, the microfibrous cellulosecontent being from 6 mass % to 80 mass % and the liquid compound contentbeing at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,a flocculant containing a salt of a polyvalent metal, a dialkyl dimethylammonium salt, and a cellulose plasticizer, the microfibrous cellulosecontent being from 6 mass % to 80 mass % and the liquid compound contentbeing at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,aluminum sulfate, a cationic surfactant, and a cellulose plasticizer,the microfibrous cellulose content being from 6 mass % to 80 mass % andthe liquid compound content being at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,a flocculant containing a salt of a polyvalent metal, a cationic polymerflocculant, and a cellulose plasticizer, the microfibrous cellulosecontent being from 6 mass % to 80 mass % and the liquid compound contentbeing at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,aluminum sulfate, a cationic polymer flocculant, and a celluloseplasticizer, the microfibrous cellulose content being from 6 mass % to80 mass % and the liquid compound content being at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,an alkali, and a cellulose plasticizer, the microfibrous cellulosecontent being from 6 mass % to 80 mass % and the liquid compound contentbeing at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,an inorganic alkali compound, and a cellulose plasticizer, themicrofibrous cellulose content being from 6 mass % to 80 mass % and theliquid compound content being at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,an anionic surfactant, and a cellulose plasticizer, the microfibrouscellulose content being from 6 mass % to 80 mass % and the liquidcompound content being at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,an anionic polymer flocculant, and a cellulose plasticizer, themicrofibrous cellulose content being from 6 mass % to 80 mass % and theliquid compound content being at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,a flocculant containing a salt of a polyvalent metal, an alkali, and acellulose plasticizer, the microfibrous cellulose content being from 6mass % to 80 mass % and the liquid compound content being at least 15mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,a flocculant containing a salt of a polyvalent metal, an inorganicalkali compound, and a cellulose plasticizer, the microfibrous cellulosecontent being from 6 mass % to 80 mass % and the liquid compound contentbeing at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,disodium hydrogen phosphate, an alkali, and a cellulose plasticizer, themicrofibrous cellulose content being from 6 mass % to 80 mass % and theliquid compound content being at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,a flocculant containing a salt of a polyvalent metal, an anionicsurfactant, and a cellulose plasticizer, the microfibrous cellulosecontent being from 6 mass % to 80 mass % and the liquid compound contentbeing at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,disodium hydrogen phosphate, an anionic surfactant, and a celluloseplasticizer, the microfibrous cellulose content being from 6 mass % to80 mass % and the liquid compound content being at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,a flocculant containing a salt of a polyvalent metal, an anionic polymerflocculant, and a cellulose plasticizer, the microfibrous cellulosecontent being from 6 mass % to 80 mass % and the liquid compound contentbeing at least 15 mass %.

The microfibrous cellulose aggregate of this embodiment containsmicrofibrous cellulose having an average fiber width of 2 nm to 50 nm, aliquid compound composed of at least one of water or an organic solvent,disodium hydrogen phosphate, an anionic polymer flocculant, and acellulose plasticizer, the microfibrous cellulose content being from 6mass % to 80 mass % and the liquid compound content being at least 15mass %.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal and an acid to the first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal and an inorganic acid to the first microfibrous cellulosedispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing aluminum sulfate and an acid to the firstmicrofibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal and a cationic surfactant to the first microfibrous cellulosedispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal and a dialkyl dimethyl ammonium salt to the first microfibrouscellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing aluminum sulfate and a cationic surfactant to thefirst microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal and a cationic polymer flocculant to the first microfibrouscellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing aluminum sulfate and a cationic polymer flocculantto the first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal and an alkali to the first microfibrous cellulose dispersionliquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal and an inorganic alkali compound to the first microfibrouscellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing disodium hydrogen phosphate and an alkali to thefirst microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal and an anionic surfactant to the first microfibrous cellulosedispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing disodium hydrogen phosphate and an anionicsurfactant to the first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal and an anionic polymer flocculant to the first microfibrouscellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing disodium hydrogen phosphate and an anionic polymerflocculant to the first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing an acid and a cellulose plasticizer to the firstmicrofibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing an inorganic acid and a cellulose plasticizer tothe first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a cationic surfactant and a cellulose plasticizerto the first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a dialkyl dimethyl ammonium salt and a celluloseplasticizer to the first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a cationic polymer flocculant and a celluloseplasticizer to the first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal, an acid, and a cellulose plasticizer to the first microfibrouscellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal, an inorganic acid, and a cellulose plasticizer to the firstmicrofibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing aluminum sulfate, an acid, and a celluloseplasticizer to the first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal, a cationic surfactant, and a cellulose plasticizer to the firstmicrofibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal, a dialkyl dimethyl ammonium salt, and a cellulose plasticizer tothe first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing aluminum sulfate, a cationic surfactant, and acellulose plasticizer to the first microfibrous cellulose dispersionliquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal, a cationic polymer flocculant, and a cellulose plasticizer to thefirst microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing aluminum sulfate, a cationic polymer flocculant,and a cellulose plasticizer to the first microfibrous cellulosedispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing an alkali and a cellulose plasticizer to the firstmicrofibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing an inorganic alkali compound and a celluloseplasticizer to the first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing an anionic surfactant and a cellulose plasticizerto the first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing an anionic polymer flocculant and a celluloseplasticizer to the first microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal, an alkali, and a cellulose plasticizer to the first microfibrouscellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal, an inorganic alkali compound, and a cellulose plasticizer to thefirst microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing disodium hydrogen phosphate, an alkali, and acellulose plasticizer to the first microfibrous cellulose dispersionliquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal, an anionic surfactant, and a cellulose plasticizer to the firstmicrofibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing disodium hydrogen phosphate, an anionicsurfactant, and a cellulose plasticizer to the first microfibrouscellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing a flocculant containing a salt of a polyvalentmetal, an anionic polymer flocculant, and a cellulose plasticizer to thefirst microfibrous cellulose dispersion liquid.

The method for manufacturing the microfibrous cellulose aggregate ofthis embodiment has a concentration step of concentrating a firstmicrofibrous cellulose dispersion liquid containing microfibrouscellulose having an average fiber width of 2 nm to 200 nm and a firstdispersion medium. The concentration step has a flocculation step offlocculating the microfibrous cellulose contained in the firstmicrofibrous cellulose dispersion liquid and a filtration step ofremoving the first dispersion medium by filtering the first microfibrouscellulose dispersion liquid after the flocculation step. In theflocculation step, the microfibrous cellulose is flocculated by adding aflocculant containing disodium hydrogen phosphate, an anionic polymerflocculant, and a cellulose plasticizer to the first microfibrouscellulose dispersion liquid.

EXAMPLES Working Example 1-1 Chemical Treatment Step

First, 20 g (in terms of absolute dry mass) of leaf bleached kraft pulp(LBKP) was prepared as a cellulose raw material so as to have a carboxygroup content of 0.06 mmol/g and a solid content concentration of 30mass % (water content: 70 mass %). The LBKP was placed in a container,and after 30 L of an ozone/oxygen mixed gas with an ozone concentrationof 200 g/m³ was introduced into the container, the container was shakenfor 2 minutes at 25° C. The ozone addition rate at this time was 30 mass% per the pulp dry mass. After the pulp was left to stand for 6 hours,the ozone and the air inside the container were removed, and ozoneoxidation treatment was ended. After the completion of treatment, theresultant was suspended and washed with ion-exchanged water, and washingwas repeated until the pH of the rinse water became 6 or higher. Theresultant was then filtered under reduced pressure using filter paper toobtain an ozone oxidized pulp with a solid content concentration of 20mass %.

Next, 200 g of a 0.3 mass % sodium chlorite aqueous solution having a pHadjusted to 4 to 5 with hydrochloric acid (equivalent to 3 mass % ofsodium chlorite per the absolute dry mass of the cellulose fibers) wasadded to 100 g of the ozone oxidized pulp (20 g in terms of absolute drymass), and additional oxidation treatment was performed by reacting theresultant for 3 hours at 70° C. After the completion of additionaloxidation treatment, the resultant was suspended and washed withion-exchanged water, and washing was repeated until the pH of the rinsewater became 6 or higher so as to obtain an oxidation-treated pulp.

A dispersion liquid with a solid content concentration of 2 mass % wasprepared by adding ion-exchanged water to the oxidation-treated pulpdescribed above (20 g in terms of absolute dry mass). Sodium hydroxidewas added to this dispersion liquid so that the sodium hydroxideconcentration was 0.3 mass %, and after this was stirred for 5 minutes,the resultant was left to stand for 30 minutes at room temperature.After the completion of treatment, the resultant was suspended andwashed with ion-exchanged water, and washing was repeated until the pHof the rinse water became 8 or lower so as to obtain a dispersion liquidcontaining an alkali-treated pulp.

(Fibrillation Step)

Next, a cellulose fiber water dispersion liquid with a cellulose fiberconcentration of 0.5 mass % was prepared by adding ion-exchanged waterto the dispersion liquid containing the alkali-treated pulp. Amicrofibrous cellulose dispersion liquid was obtained by performingfibrillation treatment on the cellulose fiber water dispersion liquidfor 30 minutes under conditions with a rotation speed of 21,500 rpmusing a fibrillation treatment device (CLEARMIX-2.2S; manufactured by MTechnique Co., Ltd.).

The obtained microfibrous cellulose dispersion liquid was centrifuged at12,000 G for 10 minutes (centrifuge: “H-200NR”; manufactured by KokusanCo., Ltd.), and the supernatant was collected. lon-exchanged water wasadded to the supernatant so as to obtain a supernatant liquid (A) with acellulose content of 0.2 mass %.

(Flocculation Step)

A gel-like aggregate of pH 2.8 was obtained by adding a 4N sulfuric acidaqueous solution (inorganic acid) to 110.5 g of the supernatant liquid(A) while stirring so as to flocculate the microfibrous cellulose.

(Filtration Step)

A PTFE membrane filter (ADVANTEC; pore size: 0.5 μm) that was immersedin isopropyl alcohol in advance was placed on a Buchner funnel typeglass filter with a sintered size of 30 μm to 50 μm (KG-90 manufacturedby ADVANTEC), and this was installed in a filtering flask. Thefiltration area at this time was 0.00441 m².

Next, the obtained gel-like aggregate was placed on the membrane filterunder atmospheric pressure at 23° C., and the gel-like aggregate wasconcentrated by performing suction filtration using an aspirator(suction pressure: 0.08 MPa) so as to obtain a microfibrous celluloseaggregate.

(Redispersion Step)

A microfibrous cellulose-containing solution was obtained by adding themicrofibrous cellulose aggregate obtained by the filtration step towater. Next, 1N sodium hydroxide was added to the microfibrouscellulose-containing solution while stirring to adjust the pH to 11.6.The total mass at this time was set to 110.5 g, which was the same asthe supernatant liquid (A) prior to the flocculation step. Amicrofibrous cellulose water dispersion liquid was obtained by thenperforming redispersion treatment for 1 minute under conditions with arotation speed of 11,000 rpm using a homomixer (ULTRA-TURRAXmanufactured by IKA).

Working Example 1-2

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 1-1 with the exception that sodiumhydroxide was not added to the microfibrous cellulose-containingsolution in the redispersion step.

Working Example 1-3

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 1-1 with the exception that theflocculation step in Working Example 1-1 was omitted and the supernatantliquid (A) was concentrated instead of the gel-like aggregate in thefiltration step.

Working Example 2-1 Chemical Treatment Step

An aqueous solution of phosphoric acid-based compound (hereinafter,called the “phosphoric acid compound reagent”) was obtained bydissolving 1.69 g of sodium dihydrogenphosphate dihydrate and 1.21 g ofdisodium hydrogenphosphate in 3.39 g of water. The pH of the phosphoricacid compound reagent was 6.0 at 25° C.

A cellulose raw material dispersion liquid was obtained by diluting thesame type of LBKP as that used in Working Example 1 with ion-exchangedwater so that the water content was 80 mass %. 6.29 g of the phosphoricacid compound reagent (20 parts by mass in terms of phosphorous elementcontent relative to 100 parts by mass of dried pulp) was added to 15 gof this cellulose raw material dispersion liquid and then dried untilthe mass became constant using a fan drier at 105° C. (DKM400; YamatoScientific Co., Ltd.) while kneading once every 15 minutes. Thereafter,the mixture was heat treated using a fan drier at 150° C. for one hour,and a phosphoric acid group was introduced into cellulose.

Next, 300 mL of ion-exchanged water was added to the cellulose in whichthe phosphoric acid group was introduced. After the mixture was washedwhile stirring, the mixture was dewatered. The dewatered pulp wasdiluted with 300 mL of ion-exchanged water. While stirring, 5 mL of a 1Nsodium hydroxide aqueous solution was added gradually to the mixture,and an alkali-treated pulp dispersion liquid having a pH of 12 to 13 wasobtained. This alkali-treated pulp dispersion liquid was then dewateredand washed by adding 300 mL of ion-exchanged water. Thisdewatering/washing was further repeated twice.

(Fibrillation Step)

After ion-exchanged water was added to the washed and dewatered pulp,the resultant was stirred so as to prepare a 0.5 mass % dispersionliquid. A microfibrous cellulose dispersion liquid was obtained byperforming fibrillation treatment on this dispersion liquid for 30minutes under conditions with a rotation speed of 21,500 rpm using afibrillation treatment device (CLEARMIX-2.2S; manufactured by MTechnique Co., Ltd.).

The obtained microfibrous cellulose dispersion liquid was centrifuged at12,000 G for 10 minutes (centrifuge: “H-200NR”; manufactured by KokusanCo., Ltd.), and the supernatant was collected. Ion-exchanged water wasadded to the supernatant so as to obtain a supernatant liquid (B) with acellulose content of 0.2 mass %.

(Flocculation Step)

A gel-like aggregate of pH 1.5 was obtained by adding a 4N sulfuric acidaqueous solution (inorganic acid) to 110.5 g of the supernatant liquid(B) while stirring so as to flocculate the microfibrous cellulose.

(Filtration Step/Redispersion Step)

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in the filtration step and the redispersion step ofWorking Example 1-1.

Working Example 2-2

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 2-1 with the exception that sodiumhydroxide was not added to the microfibrous cellulose-containingsolution in the redispersion step.

Working Example 2-3

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 2-1 with the exception that theflocculation step in Working Example 2-1 was omitted and the supernatantliquid (B) was concentrated instead of the gel-like aggregate in thefiltration step.

Working Example 3-1 Chemical Treatment Step/Fibrillation Step

A cellulose raw material dispersion liquid (pulp concentration: 2 mass%) was obtained by beating the same type of LBKP as that used in WorkingExample 1-1 for 200 minutes with a Niagara beater (volume: 23 liters;manufactured by Tozai Seiki K.K.).

The cellulose raw material dispersion liquid was dewatered to adjust theconcentration to 3 mass %, and the pH was adjusted to 6 with 0.1 mass %sulfuric acid. After the resultant was warmed to 50° C. in a warm waterbath, 3 mass % of an enzyme optimase CX7L (manufactured by Genencor) wasadded to the pulp (in terms of solid content) and reacted while stirringfor 1 hour at 50° C. to perform enzyme treatment. An enzyme treateddispersion liquid was then obtained by heating the pulp dispersionliquid at 95° C. or greater for 20 minutes and deactivating the enzyme.

The enzyme treated dispersion liquid was filtered under reduced pressurewhile washing with ion-exchanged water until the electric conductivityat a cellulose content of 1 mass % reached a prescribed value or lower(10 μS/cm) (No. 2 filter paper was used, ADVANTEC). A 0.5 mass %dispersion liquid was prepared by placing the residue on the filterpaper in ion-exchanged water and stirring. A microfibrous cellulosedispersion liquid was obtained by subjecting the dispersion liquid tomicronization treatment (fibrillation) for 30 minutes at 21,500 rpmusing a high-speed rotary type fibrillation device (CLEARMIX;manufactured by M Technique Co., Ltd.).

A supernatant liquid (C) was obtained by centrifuging the obtainedmicrofibrous cellulose dispersion liquid and adjusting the concentrationthereof in the same manner as in Working Example 1-1.

(Flocculation Step/Filtration Step/Redispersion Step)

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in the flocculation step, filtration step, andredispersion step in Working Example 1-1 using the supernatant liquid(C).

Working Example 3-2

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 3-1 with the exception that sodiumhydroxide was not added to the microfibrous cellulose-containingsolution in the redispersion step.

Working Example 3-3

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 3-1 with the exception that theflocculation step in Working Example 3-1 was omitted and the supernatantliquid (C) was concentrated instead of the gel-like aggregate in thefiltration step.

Working Example 4-1 Chemical Treatment Step/Fibrillation Step

A dried pulp with a water content of 3 mass % or less was obtained bydrying the same type of LBKP as that used in Working Example 1-1 for 3hours at 105° C. Next, an autoclave was filled with 4 g of the driedpulp and 4 g of maleic anhydride (100 parts by mass with respect to 100parts by mass of the dried pulp), and the resultant was treated for 2hours at 150° C. Next, after the pulp treated with maleic anhydride waswashed three times with 500 mL of water, ion-exchanged water was addedto prepare 490 mL of a maleic anhydride-treated pulp dispersion liquid.

Next, 10 mL of a 4N sodium hydroxide aqueous solution was graduallyadded to the maleic anhydride-treated pulp dispersion liquid whilestirring to adjust the pH range from 12 to 13, and the pulp was thussubjected to alkali treatment. The pulp after alkali treatment was thenwashed with water until the pH reached 8 or lower.

Next, an alkali-treated pulp dispersion liquid with a solid contentconcentration of 0.5 mass % was prepared by adding ion-exchanged waterto the pulp after alkali treatment.

The obtained alkali-treated pulp dispersion liquid was subjected tofibrillation treatment, centrifuged, and adjusted in concentration inthe same manner as in Working Example 1-1 so as to obtain a supernatantliquid (D).

(Flocculation Step/Filtration Step/Redispersion Step)

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in the flocculation step, filtration step, andredispersion step in Working Example 1-1 using the supernatant liquid(D).

Working Example 4-2

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 4-1 with the exception that sodiumhydroxide was not added to the microfibrous cellulose-containingsolution in the redispersion step.

Working Example 4-3

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 4-1 with the exception that theflocculation step in Working Example 4-1 was omitted and the supernatantliquid (D) was concentrated instead of the gel-like aggregate in thefiltration step.

Working Example 5-1

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 1-1 with the exception that thecentrifugation step for the microfibrous cellulose dispersion liquid inWorking Example 1-1 was omitted and a microfibrous cellulose dispersionliquid was concentrated instead of the supernatant liquid (A) in theconcentration step.

Working Example 5-2

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 5-1 with the exception that sodiumhydroxide was not added to the microfibrous cellulose-containingsolution in the redispersion step.

Working Example 5-3

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 5-1 with the exception that theflocculation step in Working Example 5-1 was omitted and a microfibrouscellulose dispersion liquid was concentrated instead of the gel-likeaggregate in the concentration step.

Working Example 6-1

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 3-1 with the exception that thecentrifugation step for the microfibrous cellulose dispersion liquid inWorking Example 3-1 was omitted and a microfibrous cellulose dispersionliquid was concentrated instead of the supernatant liquid (C) in theconcentration step.

Working Example 6-2

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 6-1 with the exception that sodiumhydroxide was not added to the microfibrous cellulose-containingsolution in the redispersion step.

Working Example 6-3

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 6-1 with the exception that theflocculation step in Working Example 6-1 was omitted and a microfibrouscellulose dispersion liquid was concentrated instead of the gel-likeaggregate in the concentration step.

Working Example 7-1 Chemical Treatment Step

A cellulose raw material dispersion liquid (pulp concentration: 2 mass%) was obtained by beating the same type of LBKP as that used in WorkingExample 1-1 for 200 minutes with a Niagara beater (volume: 23 liters;manufactured by Tozai Seiki K.K.). The obtained pulp slurry wasdewatered with a centrifugal dewatering device (manufactured by KokusanCo., Ltd.) for 15 minutes at 2000 rpm so as to concentrate the pulpconcentration to 25 mass %. Next, 60 parts by mass (dry mass) of thepulp, 7 parts by mass of sodium hydroxide, 2352 parts by mass of IPA,and 588 parts by mass of water were charged into an IKA stirrer with arotation speed adjusted to 800 rpm, and the resultant was mixed andstirred for 30 minute at 30° C. The resultant was heated to 80° C., and120 parts by mass (in terms of active component) of glycidyl trimethylammonium chloride was added as a cationization agent. After this wasreacted for 1 hour, the reaction product was extracted, neutralized,washed, and concentrated to obtain a cationized pulp with aconcentration of 25 mass %.

(Fibrillation Step)

Next, a cellulose fiber water dispersion liquid with a cellulose fiberconcentration of 0.5 mass % was prepared by adding ion-exchanged waterto the dispersion liquid containing the cationized pulp. A microfibrouscellulose dispersion liquid was obtained by performing fibrillationtreatment on the cellulose fiber water dispersion liquid for 30 minutesunder conditions with a rotation speed of 21,500 rpm using afibrillation treatment device (CLEARMIX-2.2S; manufactured by MTechnique Co., Ltd.).

The obtained microfibrous cellulose dispersion liquid was centrifuged at12,000 G for 10 minutes (centrifuge: “H-200NR”; manufactured by KokusanCo., Ltd.), and the supernatant was collected. lon-exchanged water wasadded to the supernatant so as to obtain a supernatant liquid (E) with acellulose content of 0.2 mass %.

(Flocculation Step)

A gel-like aggregate of pH 12 was obtained by adding a 1N sodiumhydroxide aqueous solution (inorganic alkali) to 110.5 g of thesupernatant liquid (E) while stirring so as to flocculate themicrofibrous cellulose.

(Filtration Step)

A PTFE membrane filter (ADVANTEC; pore size: 0.5 μm) that was immersedin isopropyl alcohol in advance was placed on a Buchner funnel typeglass filter with a sintered size of 30 μm to 50 μm (KG-90 manufacturedby ADVANTEC), and this was installed in a filtering flask. Thefiltration area at this time was 0.00441 m².

Next, the obtained gel-like aggregate was placed on the membrane filterunder atmospheric pressure at 23° C., and the gel-like aggregate wasconcentrated by performing suction filtration using an aspirator(suction pressure: 0.08 MPa) so as to obtain a microfibrous celluloseaggregate.

(Redispersion Step)

A microfibrous cellulose-containing solution was obtained by adding themicrofibrous cellulose aggregate obtained by the filtration step towater. Next, 4N hydrochloric acid was added to the microfibrouscellulose-containing solution while stirring to adjust the pH to 4.0.The total mass at this time was set to 110.5 g, which was the same asthe supernatant liquid (A) prior to the flocculation step. Next,redispersion treatment was performed for 1 minute under conditions witha rotation speed of 11,000 rpm using a homomixer (ULTRA-TURRAXmanufactured by IKA). Next, the resultant was irradiated with ultrasonicwaves for 30 seconds under conditions (cycle 1; amplitude: 100%) usingan ultrasonic disperser (UP400S, manufactured by Hielscher) so as toobtain a water dispersion of microfibrous cellulose.

Working Example 7-2

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 7-1 with the exception thathydrochloric acid was not added to the microfibrous cellulose-containingsolution in the redispersion step.

Working Example 7-3

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 7-1 with the exception that theflocculation step in Working Example 7-1 was omitted and the supernatantliquid (E) was concentrated instead of the gel-like aggregate in thefiltration step.

Working Example 8

A 20 mass % microfibrous cellulose aggregate was obtained by drying the12 mass % microfibrous cellulose aggregate obtained in the filtrationstep in Working Example 1-1 in an oven at 100° C. Using this 20 mass %microfibrous cellulose aggregate, the pH was adjusted and the aggregatewas treated with a homomixer in the same manner as in the redispersionstep of Working Example 1. The resultant was then irradiated withultrasonic waves for 30 seconds under conditions (cycle 1; amplitude:100%) using an ultrasonic disperser (UP400S, manufactured by Hielscher)so as to obtain a water dispersion of microfibrous cellulose.

Working Example 9

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 8 with the exception that a 30 mass %microfibrous cellulose aggregate was obtained by drying the 12 mass %microfibrous cellulose aggregate obtained in the filtration step inWorking Example 1-1 in an oven at 100° C.

Working Example 10

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 8 with the exception that a 47 mass %microfibrous cellulose aggregate was obtained by drying the 12 mass %microfibrous cellulose aggregate obtained in the filtration step inWorking Example 1-1 in an oven at 100° C.

Working Example 11

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 8 with the exception that a 78 mass %microfibrous cellulose aggregate was obtained by drying the 12 mass %microfibrous cellulose aggregate obtained in the filtration step inWorking Example 1-1 in an oven at 100° C.

Working Example 12

Instead of 4N sulfuric acid in the flocculation step of Working Example1-1, 4 mass %, with respect to the dry mass of the pulp, of a 2 mass %aluminum sulfate solution was added. A microfibrous cellulose waterdispersion liquid was obtained by subjecting the obtained microfibrouscellulose aggregate to the same treatment as that of the redispersionstep of Working Example 8.

Working Example 13

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 12 with the exception that 12 mass %of a polyaluminum chloride solution (Paho#2S manufactured by Asada KogyoK.K.) serving as a flocculant containing a salt of a polyvalent metalwas added with respect to the dry mass of the pulp in terms of theAl(OH)₃ content instead of 4N sulfuric acid in the flocculation step.

Working Example 14

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 7-1 with the exception that 200 mass %of a 10 mass % sodium sulfate solution serving as a flocculantcontaining a salt of a polyvalent metal was added with respect to thedry mass of the pulp instead of 1N sodium hydroxide in the flocculationstep.

Working Example 15

A microfibrous cellulose water dispersion liquid was obtained in thesame manner as in Working Example 7-1 with the exception that 100 mass %of a 10 mass % disodium hydrogen phosphate solution serving as aflocculant containing a salt of a polyvalent metal was added withrespect to the dry mass of the pulp instead of 1N sodium hydroxide inthe flocculation step.

Working Example 16

First, 10 mass % of didecyl dimethyl ammonium chloride (Catiogen DDM-PGmanufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) serving as a cationicsurfactant was added with respect to the dry mass of the pulp instead of4N sulfuric acid in the flocculation step of Working Example 1-1. Amicrofibrous cellulose water dispersion liquid was obtained bysubjecting the obtained microfibrous cellulose aggregate to the sametreatment as that of the redispersion step of Working Example 8.

Working Example 17

First, 10 mass % of 2% sodium oleate (anionic surfactant) was added withrespect to the dry mass of the pulp instead of a 1N sodium hydroxideaqueous solution in the flocculation step of Working Example 7-1. Amicrofibrous cellulose water dispersion liquid was obtained bysubjecting the obtained microfibrous cellulose aggregate to the sametreatment as that of the redispersion step of Working Example 8.

Working Example 18

First, 5,000 mass % of sorbitol (Sorbit T-70 manufactured by MitsubishiShoji Foodtech Co., Ltd.) serving as a plasticizer was added withrespect to the dry mass of the pulp in addition to 4N sulfuric acid inthe flocculation step of Working Example 9. A microfibrous cellulosewater dispersion liquid was obtained by subjecting the obtainedmicrofibrous cellulose aggregate to the same treatment as that of theredispersion step of Working Example 8.

Working Example 19

First, 5,000 mass % of ethylene glycol serving as a plasticizer wasadded with respect to the dry mass of the pulp in addition to 4Nsulfuric acid in the flocculation step of Working Example 9. Amicrofibrous cellulose water dispersion liquid was obtained bysubjecting the obtained microfibrous cellulose aggregate to the sametreatment as that of the redispersion step of Working Example 8.

Working Example 20

First, 5,000 mass % of glycerin serving as a plasticizer was added withrespect to the dry mass of the pulp in addition to 4N sulfuric acid inthe flocculation step of Working Example 9. A microfibrous cellulosewater dispersion liquid was obtained by subjecting the obtainedmicrofibrous cellulose aggregate to the same treatment as that of theredispersion step of Working Example 8.

(Evaluation)

The average fiber width, microfibrous cellulose content, liquid compoundcontent, pH, filtration time at the time of concentration, andredispersibility of the microfibrous cellulose were measured for themicrofibrous cellulose aggregate of each working example using thefollowing methods. The results of the measurements are shown in Tables 1to 3.

[Average Fiber Width]

The average fiber width was measured with the method described inparagraph [0012] above.

[Microfibrous Cellulose Content]

After the mass of the microfibrous cellulose aggregate was measured, theaggregate was heated and dried for 12 hours at 105° C. to prepare adried product, and the mass of the dried product was measured. Themicrofibrous cellulose content was then determined from the formula[(mass of the dried product)/(mass of the microfibrous celluloseaggregate)]×100.

[Liquid Compound Content]

The liquid compound content was determined from the formula [(mass ofthe microfibrous cellulose aggregate−mass of the dried product−mass ofthe added acid, alkali, or flocculant)/(mass of the microfibrouscellulose aggregate)]×100.

[pH]

The pH was measured at 23° C. using a pH meter.

[Filtration Time]

The time required for the microfibrous cellulose aggregate to beobtained from the gel-like aggregate in the filtration step wasmeasured. The measurement of the filtration time was ended at the pointwhen the glossiness of the microfibrous cellulose aggregate surfacedisappeared and the filtrate mass reached 97% of the liquid massmeasured when filtration was begun.

[Redispersibility]

The haze of the supernatant liquid prior to concentration (supernatantliquid prior to the flocculation step) and the haze of the waterdispersion of microfibrous cellulose after redispersion were measuredfor Working Examples 1 to 4 and 7 to 20 using a haze meter HM-150manufactured by Murakami Color Research Laboratory Co., Ltd.

The haze of the microfibrous cellulose dispersion liquid prior toconcentration (microfibrous cellulose dispersion liquid prior to theflocculation step) and the haze of the water dispersion of microfibrouscellulose after redispersion were measured for Working Examples 5 and 6using a haze meter HM-150 manufactured by Murakami Color ResearchLaboratory Co., Ltd.

The redispersibility is superior when the difference between the haze ofthe supernatant liquid or the microfibrous cellulose dispersion liquidprior to concentration and the haze of the water dispersion ofmicrofibrous cellulose after redispersion is smaller.

TABLE 1 Microfibrous cellulose -containing substance Haze of themicrofibrous Additives at Liquid cellulose water dispersion liquid thetime of the Average Microfibrous compound (%) Chemical Type offunctional Functional group Surface flocculation fiber width cellulosecontent content Filtration Prior to treatment group amount (mmol/g)charge step (nm) (mass %) (mass %) pH time (min) concentration Afterredispersion Working Ozone treatment Carboxy group 0.445 NegativeSulfuric acid 4 12.0 86.0 3.2 10 10.0 10.7 Example 1-1 Working Sulfuricacid 17.0 Example 1-2 Working None 10.2 89.8 6.9 140 10.8 Example 1-3Working Phosphoric acid Phosphoric acid 0.736 Negative Sulfuric acid 411.5 86.4 1.6 25 18.0 20.4 Example 2-1 treatment group Working Sulfuricacid 29.2 Example 2-2 Working None 9.6 90.4 7.4 300 20.2 Example 2-3Working Enzyme Carboxy group 0.06 Negative Sulfuric acid 10 17.0 81.03.6 8 50.8 52.0 Example 3-1 treatment Working Sulfuric acid 59.9 Example3-2 Working None 15.5 84.5 6.0 55 51.0 Example 3-3 Working Maleic acidCarboxy group 0.629 Negative Sulfuric acid 4 11.8 85.9 3.1 31 15.5 14.9Example 4-1 treatment Working Sulfuric acid 27.3 Example 4-2 WorkingNone 9.8 90.2 6.6 360 26.6 Example 4-3 Working Ozone treatment Carboxygroup 0.445 Negative Sulfuric acid 80 23.0 74.5 3.2 2 23.6 23.3 Example5-1 Working Sulfuric acid 28.6 Example 5-2 Working None 20.0 80.0 6.9100 22.9 Example 5-3 Working Enzyme Carboxy group 0.06 Negative Sulfuricacid 140 25.2 72.6 3.6 3 89.0 88.7 Example 6-1 treatment WorkingSulfuric acid 92.0 Example 6-2 Working None 21.1 88.9 6.0 60 89.2Example 6-3 Working Cationization Quaternary 0.729 Positive Sodium 415.0 82.9 11.6 44 24.0 18.5 Example 7-1 agent treatment ammonium grouphydroxide Working Sulfuric acid 22.5 Example 7-2 Working None 14.0 86.06.5 168 20.2 Example 7-3

TABLE 2 Microfibrous cellulose - containing substance Additives atMicrofibrous the time of the Average cellulose Chemical Type offunctional Functional group Surface flocculation fiber width contenttreatment group amount (mmol/g) charge step (nm) (mass %) Working Ozonetreatment Carboxy group 0.445 Negative Sulfuric acid 4 20.0 Example 8Working Carboxy group 0.445 Negative Sulfuric acid 4 30.0 Example 9Working Carboxy group 0.445 Negative Sulfuric acid 4 47.0 Example 10Working Carboxy group 0.445 Negative Sulfuric acid 4 78.0 Example 11Working Carboxy group 0.445 Negative Aluminum 4 15.5 Example 12 sulfateWorking Carboxy group 0.445 Negative Polyaluminum 4 16.6 Example 13chloride Working Cationization Quaternary 0.729 Positive Sodium sulfate4 13.3 Example 14 agent treatment ammonium group Working Quaternary0.729 Positive Disodium 4 13.2 Example 15 ammonium group hydrogenphosphate Microfibrous cellulose - containing substance Haze of theLiquid microfibrous cellulose compound water dispersion liquid (%)Chemical content Filtration Prior to After treatment (mass %) pH time(min) concentration redispersion Working Ozone treatment 77.7 3.2 1010.0 6.2 Example 8 Working 67.7 3.2 10 10.0 7.2 Example 9 Working 50.93.2 10 10.0 8.3 Example 10 Working 20.0 3.2 10 10.0 8.8 Example 11Working 81.0 4.1 6 10.0 5.4 Example 12 Working 63.4 4.5 11 10.0 7.8Example 13 Working Cationization 77.8 7.5 35 24.0 24.5 Example 14 agenttreatment Working 79.0 8.3 33 24.0 25.0 Example 15

TABLE 3 Microfibrous cellulose - containing substance Additives atMicrofibrous the time of the Average cellulose Chemical Type offunctional Functional group Surface flocculation fiber width contenttreatment group amount (mmol/g) charge step (nm) (mass %) Working Ozonetreatment Carboxy group 0.445 Negative Didecyl 4 12.0 Example 16dimethyl ammonium chloride Working Cationization Quaternary 0.729Positive Sodium oleate 4 12.0 Example 17 agent treatment ammonium groupWorking Ozone treatment Carboxy group 0.445 Negative Sulfuric acid + 430.0 Example 18 sorbitol Working Carboxy group 0.445 Negative Sulfuricacid + 4 30.0 Example 19 ethylene glycol Working Carboxy group 0.445Negative Sulfuric acid + 4 30.0 Example 20 glycerin Microfibrouscellulose - containing substance Haze of the Liquid microfibrouscellulose compound water dispersion liquid (%) Chemical contentFiltration Prior to After treatment (mass %) pH time (min) concentrationredispersion Working Ozone treatment 86.5 6.9 11 10.0 8.9 Example 16Working Cationization 86.7 6.9 12 10.0 10.8 Example 17 agent treatmentWorking Ozone treatment 59.6 3.2 55 10.0 6.0 Example 18 Working 65.5 3.210 10.0 6.3 Example 19 Working 64.2 3.2 18 10.0 6.2 Example 20

In each working example, it was possible to obtain a water dispersionliquid of microfibrous cellulose by redispersing the microfibrouscellulose aggregate.

In addition, in the working examples in which microfibrous celluloseaggregates were obtained via the flocculation step and the filtrationstep after the fibrillation step (Working Examples 1-1, 1-2, 2-1, 2-2,3-1, 3-2, 4-1, 4-2, 5-1, 5-2, 6-1, 6-2, 7-1, 7-2, and 8 to 20), thefiltration time was short and the redispersibility of microfibrouscellulose was excellent. Furthermore, in Working Examples 1-1, 2-1, 3-1,4-1, 5-1, 6-1, 8 to 13, 16, and 18 to 20 in which sodium hydroxide wasadded at the time of redispersion, the redispersibility of microfibrouscellulose was particularly excellent. In addition, in Working Examples7-1, 14, 15, and 17 in which hydrochloric acid was added at the time ofredispersion, the redispersibility of microfibrous cellulose wasparticularly excellent. Moreover, in the case of Working Examples 18 to20 in which the microfibrous cellulose aggregate contained a celluloseplasticizer, the redispersibility of microfibrous cellulose wasparticularly excellent.

In the working examples in which the microfibrous cellulose aggregatewas obtained by omitting the flocculation step (Working Examples 1-3,2-3, 3-3, 4-3, 5-3, 6-3, and 7-3), the filtration time became long.

INDUSTRIAL APPLICABILITY

A microfibrous cellulose aggregate capable of reducing the shipping costand storage cost per unit microfibrous cellulose can be provided. Inaddition, a method for manufacturing this microfibrous celluloseaggregate can be provided.

1. A microfibrous cellulose aggregate comprising: microfibrous cellulose having an average fiber width of 2 nm to 50 nm; and a liquid compound comprising at least one of water or an organic solvent; wherein a content of the microfibrous cellulose is from 6 mass % to 80 mass % per a mass of an entire microfibrous cellulose aggregate; and a content of the liquid compound is at least 15 mass % per the mass of the entire microfibrous cellulose aggregate.
 2. The microfibrous cellulose aggregate according to claim 1, further comprising a flocculant containing a salt of a polyvalent metal.
 3. The microfibrous cellulose aggregate according to claim 1, further comprising at least one selected from the group consisting of acids, cationic surfactants, and cationic polymer flocculants.
 4. The microfibrous cellulose aggregate according to claim 1, further comprising at least one selected from the group consisting of alkalis, anionic surfactants, and anionic polymer flocculants.
 5. The microfibrous cellulose aggregate according to claim 2, further comprising a cellulose plasticizer.
 6. The microfibrous cellulose aggregate according to claim 1, wherein at least 40 mass % of a solid content contained in the microfibrous cellulose aggregate is the microfibrous cellulose.
 7. The microfibrous cellulose aggregate according to claim 1, wherein a maximum fiber width of the microfibrous cellulose is at most 50 nm.
 8. A method for manufacturing a microfibrous cellulose aggregate comprising a concentration step of concentrating a first microfibrous cellulose dispersion liquid containing microfibrous cellulose having an average fiber width of 2 nm to 200 nm and a first dispersion medium.
 9. The method for manufacturing a microfibrous cellulose aggregate according to claim 8, wherein the concentration step comprises a flocculation step of flocculating the microfibrous cellulose contained in the first microfibrous cellulose dispersion liquid, and a filtration step of removing the first dispersion medium by filtering the first microfibrous cellulose dispersion liquid after the flocculation step.
 10. The method for manufacturing a microfibrous cellulose aggregate according to claim 9, wherein in the flocculation step, the microfibrous cellulose is flocculated by adding a flocculant containing a salt of a polyvalent metal to the first microfibrous cellulose dispersion liquid.
 11. The method for manufacturing a microfibrous cellulose aggregate according to claim 9, wherein if a surface charge of the microfibrous cellulose is negative, the microfibrous cellulose is flocculated in the flocculation step by adding at least one selected from the group consisting of acids, cationic surfactants, and cationic polymer flocculants to the first microfibrous cellulose dispersion liquid.
 12. The method for manufacturing a microfibrous cellulose aggregate according to claim 9, wherein if a surface charge of the microfibrous cellulose is positive, the microfibrous cellulose is flocculated in the flocculation step by adding at least one selected from the group consisting of alkalis, anionic surfactants, and anionic polymer flocculants to the first microfibrous cellulose dispersion liquid.
 13. The microfibrous cellulose aggregate according to claim 9, wherein the flocculation step comprises adding a cellulose plasticizer to the microfibrous cellulose aggregate.
 14. The method for manufacturing a microfibrous cellulose aggregate according to claim 8, wherein a microfibrous cellulose content of the first microfibrous cellulose dispersion liquid is less than 6 mass % per the mass of the entire microfibrous cellulose aggregate.
 15. The method for manufacturing a microfibrous cellulose aggregate according to claim 14, wherein in the concentration step, the microfibrous cellulose dispersion liquid is concentrated so that a content of the microfibrous cellulose is from 6 mass % to 80 mass % per the mass of the entire microfibrous cellulose aggregate.
 16. A method for remanufacturing a microfibrous cellulose dispersion liquid comprising a redispersion step of preparing a second microfibrous cellulose-containing solution by adding a second dispersion medium to the microfibrous cellulose aggregate obtained by the method for manufacturing a microfibrous cellulose aggregate according to claim 8, and performing dispersion treatment on the second microfibrous cellulose-containing solution.
 17. The method for remanufacturing a microfibrous cellulose dispersion liquid according to claim 16, wherein in the redispersion step, if a surface charge of the microfibrous cellulose is negative, the second microfibrous cellulose-containing solution is adjusted to above pH 7 and below pH 12, and if the surface charge of the microfibrous cellulose is positive, the second microfibrous cellulose-containing solution is adjusted to within a range of pH 4 to pH
 7. 